Polymers

Research

Jump to: Review

15 pages, 5705 KiB

Open AccessArticle

CO₂-Philic Thin Film Composite Membranes: Synthesis and Characterization of PAN-r-PEGMA Copolymer

by Madhavan Karunakaran, Mahendra Kumar^*, Rahul Shevate, Faheem Hassan Akhtar

and Klaus-Viktor Peinemann

Advanced Membranes and Porous Materials Center, 4700 King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia

Polymers 2017, 9(7), 219; https://doi.org/10.3390/polym9070219 - 6 Jul 2017

Cited by 19 | Viewed by 7460

Abstract

In this work, we report the successful fabrication of CO₂-philic polymer composite membranes using a polyacrylonitrile-r-poly(ethylene glycol) methyl ether methacrylate (PAN-r-PEGMA) copolymer. The series of PAN-r-PEGMA copolymers with various amounts of PEG content was synthesized [...] Read more.

In this work, we report the successful fabrication of CO₂-philic polymer composite membranes using a polyacrylonitrile-r-poly(ethylene glycol) methyl ether methacrylate (PAN-r-PEGMA) copolymer. The series of PAN-r-PEGMA copolymers with various amounts of PEG content was synthesized by free radical polymerization in presence of AIBN initiator and the obtained copolymers were used for the fabrication of composite membranes. The synthesized copolymers show high molecular weights in the range of 44–56 kDa. We were able to fabricate thin film composite (TFC) membranes by dip coating procedure using PAN-r-PEGMA copolymers and the porous PAN support membrane. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were applied to analyze the surface morphology of the composite membranes. The microscopy analysis reveals the formation of the defect free skin selective layer of PAN-r-PEGMA copolymer over the porous PAN support membrane. Selective layer thickness of the composite membranes was in the range of 1.32–1.42 μm. The resulting composite membrane has CO₂ a permeance of 1.37 × 10⁻¹ m³/m²·h·bar and an ideal CO₂/N₂, selectivity of 65. The TFC membranes showed increasing ideal gas pair selectivities in the order CO₂/N₂ > CO₂/CH₄ > CO₂/H₂. In addition, the fabricated composite membranes were tested for long-term single gas permeation measurement and these membranes have remarkable stability, proving that they are good candidates for CO₂ separation. Full article

▼ Show Figures

Graphical abstract

16 pages, 13126 KiB

Open AccessArticle

Direct Micromachining of Microfluidic Channels on Biodegradable Materials Using Laser Ablation

by Yi-Kong Hsieh^1,2, Shiau-Chen Chen¹, Wen-Ling Huang², Kai-Ping Hsu¹, Kaiser Alejandro Villalobos Gorday¹, Tsinghai Wang² and Jane Wang^1,*

¹ Department of Chemical Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan

² Department of Biomedical Engineering and Environment Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan

Polymers 2017, 9(7), 242; https://doi.org/10.3390/polym9070242 - 23 Jun 2017

Cited by 60 | Viewed by 9402

Abstract

Laser patterning on polymeric materials is considered a green and rapid manufacturing process with low material selection barrier and high adjustability. Unlike microelectromechanical systems (MEMS), it is a highly flexible processing method, especially useful for prototyping. This study focuses on the development of [...] Read more.

Laser patterning on polymeric materials is considered a green and rapid manufacturing process with low material selection barrier and high adjustability. Unlike microelectromechanical systems (MEMS), it is a highly flexible processing method, especially useful for prototyping. This study focuses on the development of polymer surface modification method using a 193 nm excimer laser system for the design and fabrication of a microfluidic system similar to that of natural vasculatures. Besides from poly(dimethyl siloxane) (PDMS), laser ablation on biodegradable polymeric material, poly(glycerol sebacate) (PGS) and poly(1,3-diamino-2-hydroxypropane-co-polyol sebacate) (APS) are investigated. Parameters of laser ablation and fabrication techniques to create microchannels are discussed. The results show that nano/micro-sized fractures and cracks are generally observed across PDMS surface after laser ablation, but not on PGS and APS surfaces. The widths of channels are more precise on PGS and APS than those on PDMS. Laser beam size and channel depth are high correlation with a linear relationship. Repeated laser ablations on the same position of scaffolds reveal that the ablation efficiencies and edge quality on PGS and APS are higher than on PDMS, suggesting the high applicability of direct laser machining to PGS and APS. To ensure stable ablation efficiency, effects of defocus distance into polymer surfaces toward laser ablation stability are investigated. The depth of channel is related to the ratio of firing frequency and ablation progression speed. The hydrodynamic simulation of channels suggests that natural blood vessel is similar to the laser patterned U-shaped channels, and the resulting micro-patterns are highly applicable in the field of micro-fabrication and biomedical engineering. Full article

(This article belongs to the Special Issue Functionally Responsive Polymeric Materials)

▼ Show Figures

Graphical abstract

11 pages, 5018 KiB

Open AccessArticle

Fracture Failure Mechanisms of Long Single PA6 Fibers

by Huiling Ding^1,2, Yongzhen Zhang^3,* and Zhitao He²

¹ School of Mechanical Engineering, Northwestern Polytechnical University, Xi’an 710000, China

² School of Agricultural Equipment Engineering, Henan University of Science and Technology, Luoyang 471023, China

³ School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang 471023, China

Polymers 2017, 9(7), 243; https://doi.org/10.3390/polym9070243 - 23 Jun 2017

Cited by 6 | Viewed by 8561

Abstract

The present study investigates the failure mechanisms of industrial fiber materials, using a custom designed fiber cutting performance test bench. The fracture morphologies of single PA6 fibers are examined by scanning electron microscopy. The analysis reveals that fiber cutting can be distinguished according [...] Read more.

The present study investigates the failure mechanisms of industrial fiber materials, using a custom designed fiber cutting performance test bench. The fracture morphologies of single PA6 fibers are examined by scanning electron microscopy. The analysis reveals that fiber cutting can be distinguished according to four distinct stages of fiber failure represented by shearing, cutting, brittle fracture, and tensile failure, which are the result of different mechanisms active during the processes of crack initiation, extension, and fracture. The results of fractographic analysis are further verified by an analysis of the blade assembly speed with respect to time over the entire fracture failure process based on high-speed camera data. The results of fractographic analysis and blade assembly speed are fully consistent. Full article

▼ Show Figures

Graphical abstract

15 pages, 2541 KiB

Open AccessArticle

The Combined Effects of Environmental Conditioning and Sustained Load on Mechanical Properties of Wet Lay-Up Fiber Reinforced Polymer

by Shan Li¹, Jiyue Hu¹ and Huitao Ren^2,*

¹ The School of Civil Engineering, Wuhan University, Wuhan 430072, China

² The School of Civil Engineering, Dalian University of Technology, Dalian 116024, China

Polymers 2017, 9(7), 244; https://doi.org/10.3390/polym9070244 - 23 Jun 2017

Cited by 36 | Viewed by 5489

Abstract

The aim of this study was to investigate the combined effects of an aggressive environment and sustained load on the mechanical properties of wet lay-up fiber reinforced polymers (FRP). A total of 390 specimens, including 234 carbon fiber reinforced polymer (CFRP) specimens and [...] Read more.

The aim of this study was to investigate the combined effects of an aggressive environment and sustained load on the mechanical properties of wet lay-up fiber reinforced polymers (FRP). A total of 390 specimens, including 234 carbon fiber reinforced polymer (CFRP) specimens and 156 glass fiber reinforced polymer (GFRP) specimens, were exposed to freeze–thaw cycles, hygrothermal aging, and wet–dry cycles either in an unstressed state or loaded to about 30% or 60% of the initial ultimate load. Uniaxial tension tests were conducted on the samples after specific exposure time as well as on the control samples; and tensile properties were measured for each specimen. The results showed that the three environmental exposures, particularly hygrothermal aging, led to a significant decrease in tensile strength and elongation of the CFRP and GFRP specimens even for relatively short conditioning periods, and this decrease was markedly exacerbated by higher external loading levels. It was interesting to observe that the tensile modulus of the CFRP and GFRP specimens exhibited an excellent resistance and even appeared to increase slightly after exposure. Finally, predictive values of tensile strength based on the Arrhenius method were compared with the design values of ACI 440.2R-08 and GB 50608-2010. The results showed that both ACI 440.2R-08 and GB 50608-2010 were too conservative and significantly underestimated the tensile strength of FRP materials after an anticipated exposure period. Full article

▼ Show Figures

Graphical abstract

26 pages, 553 KiB

Open AccessArticle

Dynamics of a Polymer Network Based on Dual Sierpinski Gasket and Dendrimer: A Theoretical Approach

by Aurel Jurjiu^*, Teodor-Lucian Biter and Flaviu Turcu

Faculty of Physics, Babes-Bolyai University, Street Mihail Kogalniceanu 1, 400084 Cluj-Napoca, Romania

Polymers 2017, 9(7), 245; https://doi.org/10.3390/polym9070245 - 24 Jun 2017

Cited by 11 | Viewed by 4609

Abstract

In this paper we focus on the relaxation dynamics of a multihierarchical polymer network built through the replication of the dual Sierpinski gasket in the form of a regular dendrimer. The relaxation dynamics of this multihierarchical structure is investigated in the framework of [...] Read more.

In this paper we focus on the relaxation dynamics of a multihierarchical polymer network built through the replication of the dual Sierpinski gasket in the form of a regular dendrimer. The relaxation dynamics of this multihierarchical structure is investigated in the framework of the generalized Gaussian structure model using both Rouse and Zimm approaches. In the Rouse-type approach, we show a method whereby the whole eigenvalue spectrum of the connectivity matrix of the multihierarchical structure can be determined iteratively, thereby rendering possible the analysis of the Rouse-dynamics at very large generations. Remarkably, the general picture that emerges from both approaches, even though we have a mixed growth algorithm and the monomers interactions are taken into account specifically to the adopted approach, is that the multihierarchical structure preserves the individual relaxation behaviors of its constituent components. The theoretical findings with respect to the splitting of the intermediate domain of the relaxation quantities are well supported by experimental results. Full article

▼ Show Figures

Figure 1

13 pages, 3554 KiB

Open AccessArticle

Photodeprotectable N-Alkoxybenzyl Aromatic Polyamides

by Kenichi Iwashita^1,2,*, Hironobu Katoh², Yoshihiro Ohta² and Tsutomu Yokozawa^2,*

¹ Photosensitive Material R&D Department, Hitachi Chemical Co. Ltd., 4-13-1 Hitachi, Ibaraki 317-8555, Japan

² Department of Materials and Life Chemistry, Kanagawa University, Rokkakubashi, Kanagawa-ku, Yokohama 221-8686, Japan

Polymers 2017, 9(7), 246; https://doi.org/10.3390/polym9070246 - 24 Jun 2017

Cited by 7 | Viewed by 6339

Abstract

N-alkoxybenzyl aromatic polyamides were synthesized by polycondensation of N-alkoxybenzyl aromatic diamine with equimolar dicarboxylic acid chloride in the presence of 2.2 equiv. of pyridine at room temperature for 2 days. The obtained polyamides were mainly cyclic polymers, as determined by means [...] Read more.

N-alkoxybenzyl aromatic polyamides were synthesized by polycondensation of N-alkoxybenzyl aromatic diamine with equimolar dicarboxylic acid chloride in the presence of 2.2 equiv. of pyridine at room temperature for 2 days. The obtained polyamides were mainly cyclic polymers, as determined by means of matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry, and showed higher solubility in organic solvents than unprotected aromatic polyamides. Photodeprotection of N-alkoxybenzyl aromatic polyamide film containing photo acid generator (PAG) proceeded well under UV irradiation (5 J/cm²), followed by heating at 130 °C for 15 min. The nature of the polymer end groups of N-alkoxybenzyl aromatic polyamides was found to be crucial for photodeprotection reactivity. These polymers are promising candidates for photosensitive heat-resistant materials for fine Cu wiring formation by electroless Cu plating of high-density semiconductor packaging substrates. Full article

(This article belongs to the Special Issue Functionally Responsive Polymeric Materials)

▼ Show Figures

Graphical abstract

11 pages, 6653 KiB

Open AccessArticle

Preparation and Characterization of Chitosan/Soy Protein Isolate Nanocomposite Film Reinforced by Cu Nanoclusters

by Kuang Li^1,2,3

, Shicun Jin^1,2,3, Xiaorong Liu^1,2,3, Hui Chen^1,2,3,*, Jing He^1,2,3,* and Jianzhang Li^1,2,3,*

¹ Key Laboratory of Wood Materials Science and Utilization, Beijing Forestry University, Ministry of Education, Beijing 100083, China

² Beijing Key Laboratory of Wood Science and Engineering, Beijing Forestry University, Beijing 100083, China

³ College of Materials Science and Technology, Beijing Forestry University, Beijing 100083, China

Polymers 2017, 9(7), 247; https://doi.org/10.3390/polym9070247 - 25 Jun 2017

Cited by 69 | Viewed by 7772

Abstract

Soy protein isolate (SPI) based films have received considerable attention for use in packaging materials. However, SPI-based films exhibit relatively poor mechanical properties and water resistance ability. To tackle these challenges, chitosan (CS) and endogenous Cu nanoclusters (NCs) capped with protein were proposed [...] Read more.

Soy protein isolate (SPI) based films have received considerable attention for use in packaging materials. However, SPI-based films exhibit relatively poor mechanical properties and water resistance ability. To tackle these challenges, chitosan (CS) and endogenous Cu nanoclusters (NCs) capped with protein were proposed and designed to modify SPI-based films. Attenuated total reflectance-Fourier transform infrared spectroscopy and X-ray diffraction patterns of composite films demonstrated that interactions, such as hydrogen bonds in the film forming process, promoted the cross-linking of composite films. The surface microstructure of CS/SPI films modified with Cu NCs was more uniform and transmission electron microscopy (TEM) showed that uniform and discrete clusters were formed. Compared with untreated SPI films, the tensile strength and elongation at break of composite films were simultaneously improved by 118.78% and 74.93%, respectively. Moreover, these composite films also exhibited higher water contact angle and degradation temperature than that of pure SPI film. The water vapor permeation of the modified film also decreased. These improved properties of functional bio-polymers show great potential as food packaging materials. Full article

(This article belongs to the Collection Polysaccharides)

▼ Show Figures

Graphical abstract

11 pages, 6554 KiB

Open AccessArticle

Chestnut Honey Impregnated Carboxymethyl Cellulose Hydrogel for Diabetic Ulcer Healing

by Jong-Seok Park^*

, Sung-Jun An, Sung-In Jeong, Hui-Jeong Gwon, Youn-Mook Lim and Young-Chang Nho

Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, 1266 Sinjeong-dong, Jeongeup-si, Jeollabuk-do 580-185, Korea

Polymers 2017, 9(7), 248; https://doi.org/10.3390/polym9070248 - 27 Jun 2017

Cited by 43 | Viewed by 9518

Abstract

Honey-based wound dressings have attracted a lot of attention from modern scientists owing to their anti-inflammatory and antibacterial effects without antibiotic resistance. Such dressings also promote moist wound healing, and have been considered natural, abundant, and cheap materials for folk marketing. This study [...] Read more.

Honey-based wound dressings have attracted a lot of attention from modern scientists owing to their anti-inflammatory and antibacterial effects without antibiotic resistance. Such dressings also promote moist wound healing, and have been considered natural, abundant, and cheap materials for folk marketing. This study investigated the various behaviors and characteristics of chestnut honey-impregnated carboxymethyl cellulose sodium hydrogel paste (CH–CMC) as a therapeutic dressing, such as its moist retention, antibacterial activity for inhibiting the growth of Staphylococcus aureus and Escherichia coli, and the rate of wound healing in db/db mice. The results provide good evidence, suggesting that CH–CMC has potential as a competitive candidate for diabetic ulcer wound healing. Full article

(This article belongs to the Collection Polysaccharides)

▼ Show Figures

Figure 1

13 pages, 3956 KiB

Open AccessArticle

Facile Synthesis and Self-Assembly of Amphiphilic Polyether-Octafunctionalized Polyhedral Oligomeric Silsesquioxane via Thiol-Ene Click Reaction

by Yong Xia^1,*

, Sha Ding¹, Yuejun Liu¹ and Zhengjian Qi²

¹ Key Laboratory of Advanced Packaging Materials and Technology of Hunan Province, Hunan University of Technology, Zhuzhou 412007, China

² College of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China

Polymers 2017, 9(7), 251; https://doi.org/10.3390/polym9070251 - 28 Jun 2017

Cited by 10 | Viewed by 10228

Abstract

We demonstrated here a facile and efficient synthesis of polyhedral oligomeric silsesquioxane-based amphiphilic polymer by thiol-ene click chemistry. The properties of polyhedral oligomeric silsesquioxane (POSS)–PEG amphiphilic polymers were studied in detail by a combination of ¹H NMR, ¹³C NMR, ²⁹Si [...] Read more.

We demonstrated here a facile and efficient synthesis of polyhedral oligomeric silsesquioxane-based amphiphilic polymer by thiol-ene click chemistry. The properties of polyhedral oligomeric silsesquioxane (POSS)–PEG amphiphilic polymers were studied in detail by a combination of ¹H NMR, ¹³C NMR, ²⁹Si NMR FT-IR, GPC, and TG analysis. The newly-designed thiol-ene protocol obtains only anti-Markovnikov addition POSS-based amphiphilic polymers when compared with platinum-catalysed hydrosilylation method. The critical micelle concentration (CMC) of the resulting polymers are in the range of 0.011 to 0.050 mg/mL, and dynamic light scattering (DLS) results revealed that the obtained amphiphilic polymers can self-assemble into nanoparticles in aqueous solutions with a bimodal (two peaks) distribution. Furthermore, the specific polymer showed obvious thermo-sensitive behaviour at 45.5 °C. Full article

(This article belongs to the Collection Silicon-Containing Polymeric Materials)

▼ Show Figures

Graphical abstract

14 pages, 2560 KiB

Open AccessArticle

Tailoring Drug Release Properties by Gradual Changes in the Particle Engineering of Polysaccharide Chitosan Based Powders

by Ednaldo G. Do Nascimento¹, Lilia B. De Caland¹, Arthur S.A. De Medeiros¹, Matheus F. Fernandes-Pedrosa¹, José L. Soares-Sobrinho², Kátia S.C.R. Dos Santos³ and Arnóbio Antonio Da Silva-Júnior^1,*

¹ Laboratory of Pharmaceutical Technology and Biotechnology, Department of Pharmacy, Federal University of Rio Grande do Norte, UFRN, Gal. Gustavo Cordeiro de Farias, Petropolis, Natal 59072-570, RN, Brazil

² Department of Pharmacy, Center of Health Sciences, Federal University of Pernambuco, Professor Moraes Rego 1235, Recife 50670-901, PE, Brazil

³ School of Pharmaceutical Sciences, Federal University of Amazonas, UFAM, General Rodrigo Octávio Jordão Ramos, 6200, South Sector, Manaus 69077-000, AM, Brazil

Polymers 2017, 9(7), 253; https://doi.org/10.3390/polym9070253 - 29 Jun 2017

Cited by 19 | Viewed by 5980

Abstract

Chitosan is a natural copolymer generally available in pharmaceutical and food powders associated with drugs, vitamins, and nutraceuticals. This study focused on monitoring the effect of the morphology and structural features of the chitosan particles for controlling the release profile of the active [...] Read more.

Chitosan is a natural copolymer generally available in pharmaceutical and food powders associated with drugs, vitamins, and nutraceuticals. This study focused on monitoring the effect of the morphology and structural features of the chitosan particles for controlling the release profile of the active pharmaceutical ingredient (API) propranolol hydrochloride. Chitosan with distinct molecular mass (low and medium) were used in the formulations as crystalline and irregular particles from commercial raw material, or as spherical, uniform, and amorphous spray-dried particles. The API–copolymer interactions were assessed when adding the drug before (drug-loaded particles) or after the spray drying (only mixed with blank particles). The formulations were further compared with physical mixtures of the API with chitin and microcrystalline cellulose. The scanning electron microscopy (SEM) images, surface area, particle size measurements, X-ray diffraction (XRD) analysis and drug loading have supported the drug release behavior. The statistical analysis of experimental data demonstrated that it was possible to control the drug release behavior (immediate or slow drug release) from chitosan powders using different types of particles. Full article

(This article belongs to the Special Issue Polymers from Renewable Resources)

▼ Show Figures

Graphical abstract

13 pages, 2899 KiB

Open AccessArticle

In Vitro Response of Human Peripheral Blood Mononuclear Cells (PBMC) to Collagen Films Treated with Cold Plasma

by Rui Chen^1,2,*, Jude Curran¹, Fanrong Pu², Zhuola Zhuola¹, Yves Bayon³ and John A. Hunt^2,4

¹ Department of Mechanical, Materials and Aerospace, School of Engineering, University of Liverpool, Harrison Hughes Building, Liverpool L69 3GH, UK

² Institute of Ageing and Chronic Disease, William Henry Duncan Building, University of Liverpool, Liverpool L7 8TX, UK

³ Medtronic—Sofradim Production, 116 Avenue du Formans—BP132, F-01600 Trevoux, France

⁴ CELS Building, School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, UK

Polymers 2017, 9(7), 254; https://doi.org/10.3390/polym9070254 - 29 Jun 2017

Cited by 19 | Viewed by 9573

Abstract

The implantation of biomedical devices, including collagen-based implants, evokes an inflammatory response. Despite inflammation playing an important role in the early stages of wound healing, excessive and non-resolving inflammation may lead to the poor performance of biomaterial implants in some patients. Therefore, steps [...] Read more.

The implantation of biomedical devices, including collagen-based implants, evokes an inflammatory response. Despite inflammation playing an important role in the early stages of wound healing, excessive and non-resolving inflammation may lead to the poor performance of biomaterial implants in some patients. Therefore, steps should be taken to control the level and duration of an inflammatory response. In this study, oxygen and nitrogen gas plasmas were employed to modify the surface of collagen film, with a view to modifying the surface properties of a substrate in order to induce changes to the inflammatory response, whilst maintaining the mechanical integrity of the underlying collagen film. The effects of cold plasma treatment and resultant changes to surface properties on the non-specific inflammatory response of the immune system was investigated in vitro in direct contact cell culture by the measurement of protein expression and cytokine production after one and four days of human peripheral blood mononuclear cell (PBMC) culture. The results indicated that compared to oxygen plasma, nitrogen plasma treatment produced an anti-inflammatory effect on the collagen film by reducing the initial activation of monocytes and macrophages, which led to a lower production of pro-inflammatory cytokines IL-1β and TNFα, and higher production of anti-inflammatory cytokine IL-10. This was attributed to the combination of the amino chemical group and the significant reduction in roughness associated with the introduction of the nitrogen plasma treatment, which had an effect on the levels of activation of the adherent cell population. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Biointerface)

▼ Show Figures

Figure 1

16 pages, 6202 KiB

Open AccessArticle

Theoretical Analysis of Critical Flowable Physical Gel Cross-Linked by Metal Ions and Polyacrylamide-Derivative Associating Polymers Containing Imidazole Groups

by Hiroto Ozaki¹

, Tetsuharu Narita^2,3, Tsuyoshi Koga¹ and Tsutomu Indei^4,*

¹ Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Kyoto 615-8510, Japan

² Laboratoire Sciences et Ingénierie de la Matière Molle, PSL Research University, UPMC Univ Paris 06, ESPCI Paris, CNRS, 10 rue Vauquelin, 75231 Paris CEDEX 05, France

³ Global Station for Soft Matter, Global Institution for Collaborative Research and Education, Hokkaido University, Sapporo 001-0021, Japan

⁴ Department of Chemical and Biological Engineering, and Center for Molecular Study of Condensed Soft Matter, Illinois Institute of Technology, 3440 S. Dearborn Street, Suite 150, Chicago, IL 60616, USA

Polymers 2017, 9(7), 256; https://doi.org/10.3390/polym9070256 - 29 Jun 2017

Cited by 12 | Viewed by 6540

Abstract

When the polymer chains are cross-linked by physical bonds having a finite lifetime, the relaxation time and viscosity do not diverge at the gel point though percolation occurs. These undivergent quantities are related to the finite-sized “largest relaxed cluster,” which can relax before [...] Read more.

When the polymer chains are cross-linked by physical bonds having a finite lifetime, the relaxation time and viscosity do not diverge at the gel point though percolation occurs. These undivergent quantities are related to the finite-sized “largest relaxed cluster,” which can relax before it breaks. Its size is the key rheological parameter characterizing of the critical physical gels. In order to evaluate this characteristic size, we propose here a generalized phenomenological model for the viscoelasticity of critical physical gels. We apply the theory to the previously reported experimental result for the physical gel consisting of polyacrylamide-derivative associating polymers containing imidazole groups cross-linked by coordination bonds with Ni ions. We successfully estimate the size of the largest relaxed cluster and the fractal dimension. The size is in good agreement with that estimated from the mean-square displacement of probe particles at the gel point by microrheological measurement. We also compare this system with the poly(vinyl alcohol) hydrogel cross-linked by borate ions, and show that the difference in the cluster structures is originating from the differences of precursor chain properties such as overlap concentration and radius of gyration and of the cross-linking states in these systems. Full article

(This article belongs to the Special Issue Complex Fluid Rheology)

▼ Show Figures

Graphical abstract

15 pages, 4123 KiB

Open AccessArticle

Forensic Engineering of Advanced Polymeric Materials—Part V: Prediction Studies of Aliphatic–Aromatic Copolyester and Polylactide Commercial Blends in View of Potential Applications as Compostable Cosmetic Packages

by Wanda Sikorska^1,*, Joanna Rydz¹, Katarzyna Wolna-Stypka¹, Marta Musioł¹, Grażyna Adamus¹, Iwona Kwiecień¹

, Henryk Janeczek¹, Khadar Duale² and Marek Kowalczuk^1,2,*

¹ Centre of Polymer and Carbon Materials, Polish Academy of Sciences, 34, M. Curie-Sklodowska St., 41-819 Zabrze, Poland

² School of Biology, Chemistry and Forensic Science, Faculty of Science and Engineering, University of Wolverhampton, Wolverhampton WV1 1SB, UK

Polymers 2017, 9(7), 257; https://doi.org/10.3390/polym9070257 - 29 Jun 2017

Cited by 27 | Viewed by 7025

Abstract

The main aim of the present study was to determine the behavior of the specimens from Ecovio, in the form of dumbbell-shaped samples and films, during degradation in selected cosmetic ingredients such as water and paraffin. The (bio)degradation test of the prototype cosmetic [...] Read more.

The main aim of the present study was to determine the behavior of the specimens from Ecovio, in the form of dumbbell-shaped samples and films, during degradation in selected cosmetic ingredients such as water and paraffin. The (bio)degradation test of the prototype cosmetic package (sachet) made from a PBAT (poly[(1,4-butylene adipate)-co-(1,4-butylene terephthalate)]) and PLA (polylactide) blend was investigated under industrial composting conditions, and compared with the sample behavior during incubation in cosmetic media at 70 °C. During the degradation tests, the changes of the samples were evaluated using optical microscopy, ¹H NMR (proton nuclear magnetic resonance) and GPC (gel permeation chromatography) techniques. The structures of the degradation products were investigated using ESI-MSⁿ (mass spectrometry with electrospray ionization on positive and negative ions) analysis. The thermal properties of selected materials were determined by DSC (differential scanning calorimetry) and TGA (thermogravimetric analysis) analysis. It was concluded that the PBAT and PLA blend studied had a good stability during aging in cosmetic media, and could be recommended for long-shelf-life compostable packaging of cosmetics, especially with oily ingredients. Full article

(This article belongs to the Special Issue Biodegradable and Biobased Polyesters)

▼ Show Figures

Graphical abstract

19 pages, 7652 KiB

Open AccessArticle

Preparation and Characterization of Eco-Friendly Mg(OH)₂/Lignin Hybrid Material and Its Use as a Functional Filler for Poly(Vinyl Chloride)

by Łukasz Klapiszewski^1,*

, Jolanta Tomaszewska^2,*, Katarzyna Skórczewska²

and Teofil Jesionowski¹

¹ Institute of Chemical Technology and Engineering, Faculty of Chemical Technology, Poznan University of Technology, Berdychowo 4, PL-60965 Poznan, Poland

² Faculty of Chemical Technology and Engineering, UTP University of Science and Technology in Bydgoszcz, Seminaryjna 3, PL-85326 Bydgoszcz, Poland

Polymers 2017, 9(7), 258; https://doi.org/10.3390/polym9070258 - 30 Jun 2017

Cited by 42 | Viewed by 8898

Abstract

A functional magnesium hydroxide/lignin hybrid system was prepared by grinding and mixing the pure precursors using a planetary ball mill. In addition, the thermal stability was assessed based on the total mass loss of the hybrid system within the temperature range of 30–1000 [...] Read more.

A functional magnesium hydroxide/lignin hybrid system was prepared by grinding and mixing the pure precursors using a planetary ball mill. In addition, the thermal stability was assessed based on the total mass loss of the hybrid system within the temperature range of 30–1000 °C, which amounted to 38%. Moreover, the average particle size was at 4.9 μm as determined by the laser diffraction method. The effect of addition of the prepared and characterized Mg(OH)₂/lignin hybrid filler at concentrations ranging from 2.5 wt % to 10 wt % on the processing as well as mechanical and thermal properties of composites on the matrix of the unplasticized PVC compound was also evaluated. The addition of a filler to the poly(vinyl chloride) matrix causes a significant improvement of its thermal stability, which is approximately three times higher compared to a polymer without a filler. Furthermore, the prepared composites are additionally characterized by advantageous mechanical properties, especially higher Young’s modulus. A 10% increase in the oxygen index of PVC composites upon addition of 10 wt % hybrid fillers has also been observed, which contributes to an extended range of their application under conditions that require notable fire resistance. Full article

(This article belongs to the Special Issue Bio-inspired and Bio-based Polymers)

▼ Show Figures

Graphical abstract

15 pages, 5245 KiB

Open AccessArticle

Preparation and Property Evaluation of Conductive Hydrogel Using Poly (Vinyl Alcohol)/Polyethylene Glycol/Graphene Oxide for Human Electrocardiogram Acquisition

by Xueliang Xiao^1,†

, Guanzheng Wu^1,†, Hongtao Zhou¹, Kun Qian¹ and Jinlian Hu^2,*

¹ Key Laboratory of Eco-Textiles, Ministry of Education, Jiangnan University, Wuxi 214122, China

² Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hong Kong, China

^† These authors contributed equally to this work.

Polymers 2017, 9(7), 259; https://doi.org/10.3390/polym9070259 - 30 Jun 2017

Cited by 71 | Viewed by 14356

Abstract

Conductive hydrogel combined with Ag/AgCl electrode is widely used in the acquisition of bio-signals. However, the high adhesiveness of current commercial hydrogel causes human skin allergies and pruritus easily after wearing hydrogel for electrodes for a long time. In this paper, a novel [...] Read more.

Conductive hydrogel combined with Ag/AgCl electrode is widely used in the acquisition of bio-signals. However, the high adhesiveness of current commercial hydrogel causes human skin allergies and pruritus easily after wearing hydrogel for electrodes for a long time. In this paper, a novel conductive hydrogel with good mechanical and conductive performance was prepared using polyvinyl alcohol (PVA), polyethylene glycol (PEG), and graphene oxide (GO) nanoparticles. A cyclic freezing–thawing method was employed under processing conditions of −40 °C (8 h) and 20 °C (4 h) separately for three cycles in sequence until a strong conductive hydrogel, namely, PVA/PEG/GO gel, was obtained. Characterization (Fourier transform infrared spectroscopy, nuclear magnetic resonance, scanning electron microscopy) results indicated that the assembled hydrogel was successfully prepared with a three-dimensional network structure and, thereafter, the high strength and elasticity due to the complete polymeric net formed by dense hydrogen bonds in the freezing process. The as-made PVA/PEG/GO hydrogel was then composited with nonwoven fabric for electrocardiogram (ECG) electrodes. The ECG acquisition data indicated that the prepared hydrogel has good electro-conductivity and can obtain stable ECG signals for humans in a static state and in motion (with a small amount of drift). A comparison of results indicated that the prepared PVA/PEG/GO gel obtained the same quality of ECG signals with commercial conductive gel with fewer cases of allergies and pruritus in volunteer after six hours of wear. Full article

(This article belongs to the Special Issue Functionally Responsive Polymeric Materials)

▼ Show Figures

Graphical abstract

10 pages, 1773 KiB

Open AccessArticle

Improve Performance of Soy Flour-Based Adhesive with a Lignin-Based Resin

by Xiaochun Zhang^1,*, Yuding Zhu¹, Youming Yu¹ and Jiangang Song²

¹ School of Engineering, Zhejiang Agriculture and Forestry University, Lin’an 311300, China

² Zhejiang Yongyu Bamboo Joint-Stock Co., Ltd., Anji 313301, China

Polymers 2017, 9(7), 261; https://doi.org/10.3390/polym9070261 - 3 Jul 2017

Cited by 62 | Viewed by 8396

Abstract

A lignin-based resin (LB) was used to improve the performance of soy flour-based adhesives. Soy flour (SF), polyamidoamine-epichlorohydrin (PAE), and LB were used to develop a plywood adhesive. The solid content and viscosity of the adhesive, the functional groups, the thermo-stability, and the [...] Read more.

A lignin-based resin (LB) was used to improve the performance of soy flour-based adhesives. Soy flour (SF), polyamidoamine-epichlorohydrin (PAE), and LB were used to develop a plywood adhesive. The solid content and viscosity of the adhesive, the functional groups, the thermo-stability, and the crystallinity of the cured adhesives were characterized, and the performance of the resultant adhesive was evaluated by fabricating three-ply plywood. Results showed that the LB and PAE mixture used to modify the SF adhesive improved both dry and wet bond strength by 66.3% and 184.2%, respectively. Therefore, the PAE improved the wet bond strength, and the LB improved the dry bond strength. The improvement was attributed to: (1) the reaction of LB/PAE with the functions of the soy protein to form a cross-linking network; (2) a polycondensation reaction between the LB molecules improved the crosslinking density of the adhesive to form an interpenetration structure with cross-linked proteins; and (3) the easy penetration of the LB into the wood surface that enhanced interlocking between the wood and adhesive. Furthermore, the denser structure created by the LB and the PAE mixture improved thermal stability and decreased the crystallinity of the cured adhesive. The use of the LB and the PAE mixture increased the solid content by 35.5%, while still making its viscosity acceptable for industrial applications. Full article

(This article belongs to the Collection Polymeric Adhesives)

▼ Show Figures

Figure 1

12 pages, 1417 KiB

Open AccessArticle

Homo- and Copolymerizations of Ethylene and Norbornene Using Bis(β-ketoamino) Titanium Catalysts Containing Pyrazolone Rings

by Lixia Pei^1,2, San He¹, Jie Gao³

, Heng Liao³ and Haiyang Gao^3,*

¹ State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610550, China

² School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, China

³ School of Materials Science and Engineering, PCFM Lab, GD HPPC Lab, Sun Yat-sen University, Guangzhou 510275, China

Polymers 2017, 9(7), 262; https://doi.org/10.3390/polym9070262 - 30 Jun 2017

Cited by 13 | Viewed by 5592

Abstract

A series of bis(β-ketoamino) titanium complexes containing pyrazolone rings (1–3) have been synthesized, characterized, and used as precursors for homo- and copolymerization of ethylene and norbornene. The titanium complexes activated with methylaluminoxane (MAO) exhibited good activities for homopolymerization of [...] Read more.

A series of bis(β-ketoamino) titanium complexes containing pyrazolone rings (1–3) have been synthesized, characterized, and used as precursors for homo- and copolymerization of ethylene and norbornene. The titanium complexes activated with methylaluminoxane (MAO) exhibited good activities for homopolymerization of ethylene (E) to produce linear polyethylenes (PEs). Ethylene–norbornene copolymers (E–N) were also prepared by these catalysts with moderate activities, and influences of ligand substituents and norbornene addition on copolymer microstructure were studied in detail. Microstructure analysis of the E–N copolymers by ¹³C NMR and differential scanning calorimetry (DSC) techniques showed that alternating (ENEN) and isolated (ENEE) norbornene predominately appeared in the copolymer chain, and the NN dyad and NNN triad sequences were also present in the copolymers obtained by the less bulky catalyst 1. Full article

(This article belongs to the Special Issue Olefin Polymerization and Polyolefin)

▼ Show Figures

Graphical abstract

11 pages, 5659 KiB

Open AccessArticle

Enhancement of Thermal Diffusivity in Phase-Separated Bismaleimide/Poly(ether imide) Composite Films Containing Needle-Shaped ZnO Particles

by Shoya Uchida, Ryohei Ishige and Shinji Ando^*

Department of Chemistry and Material Engineering, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8552, Japan

Polymers 2017, 9(7), 263; https://doi.org/10.3390/polym9070263 - 2 Jul 2017

Cited by 12 | Viewed by 6683

Abstract

Phase-separated polymer blend composite films exhibiting high thermal diffusivity were prepared by blending a soluble polyimide (BPADA-MPD) and a bismaleimide (BMI) with needle-shaped zinc oxide (n-ZnO) particles followed by high-temperature curing at 250 °C. Images recorded with a field-emission scanning electron microscope (FE-SEM) [...] Read more.

Phase-separated polymer blend composite films exhibiting high thermal diffusivity were prepared by blending a soluble polyimide (BPADA-MPD) and a bismaleimide (BMI) with needle-shaped zinc oxide (n-ZnO) particles followed by high-temperature curing at 250 °C. Images recorded with a field-emission scanning electron microscope (FE-SEM) equipped with wavelength-dispersive spectroscopy (WDS) demonstrated that the spontaneously separated phases in the composite films were aligned along the out-of-plane direction, and the n-ZnO particles were selectively incorporated into the BMI phase. The out-of-plane thermal diffusivity of the composite films was significantly higher than those of the previously reported composite films at lower filler contents. Based on wide-angle X-ray diffraction (WAXD) patterns and image analysis, the enhanced thermal diffusivity was attributed to the confinement of the anisotropically shaped particles and their nearly isotropic orientation in one phase of the composite films. Full article

(This article belongs to the Special Issue High Performance Polymers)

▼ Show Figures

Figure 1

14 pages, 8795 KiB

Open AccessArticle

The Impact of Polymer Grafting from a Graphene Oxide Surface on Its Compatibility with a PDMS Matrix and the Light-Induced Actuation of the Composites

by Josef Osicka¹, Markéta Ilčíková², Miroslav Mrlik¹, Antonín Minařík¹, Vladimir Pavlinek¹ and Jaroslav Mosnáček^2,*

¹ Centre of Polymer Systems, University Institute, Tomas Bata University in Zlin, Trida T. Bati 5678, 760 01 Zlin, Czech Republic

² Polymer Institute, Slovak Academy of Sciences, Dubravska cesta 9, 845 41 Bratislava 45, Slovakia

Polymers 2017, 9(7), 264; https://doi.org/10.3390/polym9070264 - 3 Jul 2017

Cited by 24 | Viewed by 6932

Abstract

Poly(dimethyl siloxane) (PDMS)-based materials with improved photoactuation properties were prepared by the incorporation of polymer-grafted graphene oxide particles. The modification of the graphene oxide (GO) surface was achieved via a surface initiated atom transfer radical polymerization (SI ATRP) of methyl methacrylate and butyl [...] Read more.

Poly(dimethyl siloxane) (PDMS)-based materials with improved photoactuation properties were prepared by the incorporation of polymer-grafted graphene oxide particles. The modification of the graphene oxide (GO) surface was achieved via a surface initiated atom transfer radical polymerization (SI ATRP) of methyl methacrylate and butyl methacrylate. The modification was confirmed by thermogravimetric analysis, infrared spectroscopy and electron microscopy. The GO surface reduction during the SI ATRP was investigated using Raman spectroscopy and conductivity measurements. Contact angle measurements, dielectric spectroscopy and dynamic mechanical analyses were used to investigate the compatibility of the GO filler with the PDMS matrix and the influence of the GO surface modification on its physical properties and the interactions with the matrix. Finally, the thermal conductivity and photoactuation properties of the PDMS matrix and composites were compared. The incorporation of GO with grafted polymer chains, especially poly(n-butyl methacrylate), into the PDMS matrix improved the compatibility of the GO filler with the matrix, increased the energy dissipation due to the improved flexibility of the PDMS chains, enhanced the damping behavior and increased the thermal conductivity. All the changes in the properties positively affected the photoactuation behavior of the PDMS composites containing polymer-grafted GO. Full article

(This article belongs to the Special Issue Functionally Responsive Polymeric Materials)

▼ Show Figures

Graphical abstract

10 pages, 4387 KiB

Open AccessCommunication

Controlled Morphing of Microbubbles to Beaded Nanofibers via Electrically Forced Thin Film Stretching

by Zhi-Cheng Yao^1,2, Qiantailang Yuan¹, Zeeshan Ahmad³, Jie Huang⁴, Jing-Song Li¹ and Ming-Wei Chang^1,2,*

¹ Key Laboratory for Biomedical Engineering of Education, Ministry of China, Hangzhou 310027, China

² Zhejiang Provincial Key Laboratory of Cardio-Cerebral Vascular Detection Technology and Medicinal Effectiveness Appraisal, Zhejiang University, Hangzhou 310027, China

³ Leicester School of Pharmacy, De Montfort University, The Gateway, Leicester LE1 9BH, UK

⁴ Department of Mechanical Engineering, University College London, London WC1E 7JE, UK

Polymers 2017, 9(7), 265; https://doi.org/10.3390/polym9070265 - 3 Jul 2017

Cited by 12 | Viewed by 11381

Abstract

Topography and microstructure engineering are rapidly evolving areas of importance for biomedical and pharmaceutical remits. Here, PVA (Polyvinyl alcohol) microbubbles (diameter range ~126 to 414 μm) were used to fabricate beaded (beads-on) nanofibers using an electrohydrodynamic atomization (EHDA) technique. Mean fiber diameter, inter-bead [...] Read more.

Topography and microstructure engineering are rapidly evolving areas of importance for biomedical and pharmaceutical remits. Here, PVA (Polyvinyl alcohol) microbubbles (diameter range ~126 to 414 μm) were used to fabricate beaded (beads-on) nanofibers using an electrohydrodynamic atomization (EHDA) technique. Mean fiber diameter, inter-bead distance, and aspect ratio (AR) were investigated by regulating EHDA process parameters. PVA fibers (diameter range ~233 to 737 nm) were obtained possessing bead ARs in the range of ~10 to 56%. AR was used to modulate hydrophilicity and active release. Full article

▼ Show Figures

Figure 1

16 pages, 3572 KiB

Open AccessArticle

Catalyzed Synthesis and Characterization of a Novel Lignin-Based Curing Agent for the Curing of High-Performance Epoxy Resin

by Saeid Nikafshar¹

, Omid Zabihi^2,*, Yousef Moradi³, Mojtaba Ahmadi²

, Saba Amiri⁴ and Minoo Naebe²

¹ Department of Applied Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz 51666, Iran

² Institute for Frontier Materials, Deakin University, Geelong VIC 3216, Victoria, Australia

³ Department of Organic Chemistry, Faculty of Chemistry, Isfahan University of Technology, Isfahan 8415683111, Iran

⁴ Department of Applied Chemistry, Faculty of Chemistry, Urmia University, Urmia 5756151818, Iran

Polymers 2017, 9(7), 266; https://doi.org/10.3390/polym9070266 - 4 Jul 2017

Cited by 55 | Viewed by 10746

Abstract

In this study, lignin, an aromatic compound from the forestry industry, was used as a renewable material to synthesize a new aromatic amine curing agent for epoxy resin. Firstly, lignin was separated from black liquor and hydroxyl groups were converted to tosyl groups [...] Read more.

In this study, lignin, an aromatic compound from the forestry industry, was used as a renewable material to synthesize a new aromatic amine curing agent for epoxy resin. Firstly, lignin was separated from black liquor and hydroxyl groups were converted to tosyl groups as leaving groups. Then, primary amination was conducted using an ammonia solution at high pressure and temperature, in the presence of a nano-alumina-based catalyst. The structure of the nanocatalyst was confirmed by FT-IR, ICP, SEM, and XPS analyses. According to the FT-IR spectra, a demethylation reaction, the substitution of hydroxyl groups with tosyl groups, and then an amination reaction were successfully performed on lignin, which was further confirmed by the ¹³C NMR and CHNS analyses. The active hydrogen equivalent of aminated lignin was determined and three samples with 9.9 wt %, 12.9 wt %, and 15.9 wt % of aminated lignin, as curing agents, were prepared for curing the diglycidyl ether of bisphenol A (DGEBA). The thermal characteristics of the curing process of these epoxy samples were determined by DSC and TGA analyses. Moreover, the mechanical performance of the cured epoxy systems, e.g., the tensile strength and Izod impact strength, were measured, showing that in the presence of 12.9 wt % aminated lignin, the mechanical properties of the aminated lignin-epoxy system exhibited the best performance, which was competitive, compared to the epoxy systems cured by commercial aromatic curing agents. Full article

▼ Show Figures

Graphical abstract

10 pages, 5093 KiB

Open AccessArticle

A New Polymer-Based Fluorescent Chemosensor Incorporating Propane-1,3-Dione and 2,5-Diethynylbenzene Moieties for Detection of Copper(II) and Iron(III)

by Dongliang Yang¹

, Chunhui Dai²

, Yanling Hu¹, Shuli Liu¹, Lixing Weng³, Zhimin Luo¹, Yixiang Cheng^2,* and Lianhui Wang^1,*

¹ Key Laboratory for Organic Electronics & Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts & Telecommunications, 9 Wenyuan Road, Nanjing 210046, China

² Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China

³ College of Geography and Biological Information, Nanjing University of Posts and Telecommunications, Nanjing 210046, China

Polymers 2017, 9(7), 267; https://doi.org/10.3390/polym9070267 - 6 Jul 2017

Cited by 28 | Viewed by 6518

Abstract

A novel conjugated polymer (PDBDBM) was developed by the polymerization of 1,4-dioctyloxy-2,5-diethynylbenzene with 1,3-bis(4-bromophenyl)propane-1,3-dione based on Pd-catalyzed Sonogashira-coupling reaction. The obtained polymer PDBDBM exhibited bright green photoluminescence under UV irradiation. According to the metal ion titration experiments, PDBDBM showed high sensitivity and selectivity [...] Read more.

A novel conjugated polymer (PDBDBM) was developed by the polymerization of 1,4-dioctyloxy-2,5-diethynylbenzene with 1,3-bis(4-bromophenyl)propane-1,3-dione based on Pd-catalyzed Sonogashira-coupling reaction. The obtained polymer PDBDBM exhibited bright green photoluminescence under UV irradiation. According to the metal ion titration experiments, PDBDBM showed high sensitivity and selectivity for detection of Cu²⁺ and Fe³⁺ over other metal ions. The fluorescent detection limits of PDBDBM were calculated to be 5 nM for Cu²⁺ and 0.4 μM for Fe³⁺ and the Stern–Volmer quenching constant for Cu²⁺ and Fe³⁺ were found to be 1.28 × 10⁸ M⁻¹ and 2.40 × 10⁴ M⁻¹, respectively. These results indicated that the polymer can be used as a potential probe for Cu²⁺ and Fe³⁺ detection. Full article

(This article belongs to the Special Issue Polymeric Membranes)

▼ Show Figures

Graphical abstract

12 pages, 8876 KiB

Open AccessArticle

Structure of Composite Based on Polyheteroarylene Matrix and ZrO₂ Nanostars Investigated by Quantitative Nanomechanical Mapping

by Maria P. Sokolova^1,2,*

, Michael A. Smirnov^1,3, Alexander N. Bugrov^3,4, Pavel Geydt²

, Elena N. Popova³, Erkki Lahderanta², Valentin M. Svetlichnyi³ and Alexander M. Toikka¹

¹ Department of Chemical Thermodynamics & Kinetics, Saint Petersburg State University, Universitetsky pr. 26, Peterhof, Saint Petersburg 198504, Russia

² Laboratory of Physics, Lappeenranta University of Technology, Skinnarilankatu 34, 53850 Lappeenranta, Finland

³ Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoy pr. 31, Saint Petersburg 199004, Russia

⁴ Department of Physical Chemistry, Saint Petersburg Electrotechnical University “LETI”, ul. Professora Popova 5, St. Petersburg 197376, Russian

Polymers 2017, 9(7), 268; https://doi.org/10.3390/polym9070268 - 6 Jul 2017

Cited by 10 | Viewed by 5460

Abstract

It is known that structure of the interface between inorganic nanoparticles and polymers significantly influences properties of a polymer–inorganic composite. At the same time, amount of experimental researches on the structure and properties of material near the inorganic-polymer interface is low. In this [...] Read more.

It is known that structure of the interface between inorganic nanoparticles and polymers significantly influences properties of a polymer–inorganic composite. At the same time, amount of experimental researches on the structure and properties of material near the inorganic-polymer interface is low. In this work, we report for the first time the investigation of nanomechanical properties and maps of adhesion of material near the inorganic-polymer interface for the polyheteroarylene nanocomposites based on semi-crystalline poly[4,4′-bis (4″-aminophenoxy)diphenyl]imide 1,3-bis (3′,4-dicarboxyphenoxy) benzene, modified by ZrO₂ nanostars. Experiments were conducted using quantitative nanomechanical mapping (QNM) mode of atomic force microscopy (AFM) at the surface areas where holes were formed after falling out of inorganic particles. It was found that adhesion of AFM cantilever to the polymer surface is higher inside the hole than outside. This can be attributed to the presence of polar groups near ZrO₂ nanoparticle. QNM measurements revealed that polymer matrix has increased rigidity in the vicinity of the nanoparticles. Influence of ZrO₂ nanoparticles on the structure and thermal properties of semi-crystalline polyheteroarylene matrix was studied with wide-angle X-ray scattering, scanning electron microscopy, and differential scanning calorimetry. Full article

(This article belongs to the Special Issue Polymer Nanocomposites)

▼ Show Figures

Figure 1

13 pages, 10645 KiB

Open AccessArticle

Effect of Nanofibrillated Cellulose Content on the Temperature and Near Infrared Responses of Polyvinyl Butyral Nanofibers-Containing Bilayer Hydrogel System

by Qian Zhao¹, Luping Ning¹, Yunhong Liang^1,2,*, Zhihui Zhang^1,2 and Luquan Ren¹

¹ The Key Laboratory of Bionic Engineering, Ministry of Education, Jilin University, Changchun 130025, China

² State Key Laboratory of Automotive Simulation and Control, Jilin University, Changchun 130025, China

Polymers 2017, 9(7), 270; https://doi.org/10.3390/polym9070270 - 6 Jul 2017

Cited by 9 | Viewed by 6123

Abstract

A novel kind of nanofibrillated cellulose (NFC) reinforced polyvinyl butyral (PVB) nanofibers-containing bilayer hydrogel system was successfully fabricated via the combination of a one-step, in-situ, free radical polymerization and electrospinning. The hydrogel owned high mechanical strength, thermoresponsive, and near infrared bending/unbending properties. The [...] Read more.

A novel kind of nanofibrillated cellulose (NFC) reinforced polyvinyl butyral (PVB) nanofibers-containing bilayer hydrogel system was successfully fabricated via the combination of a one-step, in-situ, free radical polymerization and electrospinning. The hydrogel owned high mechanical strength, thermoresponsive, and near infrared bending/unbending properties. The cross-linking density of hydrogels enhanced along with the increase of NFC content. The addition of NFC and PVB nanofibers presented tiny influence on the variation of chemical bond and volume phase transition temperature. The combination between NFC and PVB nanofibers enhanced the mechanical strength and decreased the strain value, which built the base for high bonding strength of two layers and efficient thermoresponsive and near infrared responses. With the increase of NFC content, the bending degree became smaller. The bilayer hydrogel dimensions affected the deformation degree. Bilayer hydrogels with different NFC content own different deformation abilities, which can be designed as different parts of soft actuators and provide superior performance to satisfy various practical application demands. Full article

(This article belongs to the Collection Polysaccharides)

▼ Show Figures

Graphical abstract

9 pages, 3327 KiB

Open AccessArticle

Poly(3,3-dibenzyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine)/Platinum Composite Films as Potential Counter Electrodes for Dye-Sensitized Solar Cells

by Jung-Chuan Chou^1,2

, Yu-Chi Huang³, Tzi-Yi Wu^3,*

, Yi-Hung Liao⁴, Chih-Hsien Lai^1,2

, Chia-Ming Chu² and Yu-Jen Lin¹

¹ Graduate School of Electronic Engineering, National Yunlin University of Science and Technology, Yunlin 64002, Taiwan

² Department of Electronic Engineering, National Yunlin University of Science and Technology, Yunlin 64002, Taiwan

³ Graduate School of Chemical and Materials Engineering, National Yunlin University of Science and Technology, Yunlin 64002, Taiwan

⁴ Department of Information and Electronic Commerce Management, TransWorld University, Yunlin 64063, Taiwan

Polymers 2017, 9(7), 271; https://doi.org/10.3390/polym9070271 - 7 Jul 2017

Cited by 10 | Viewed by 4967

Abstract

In this study, poly(3,3-dibenzyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine)/platinum composite films (PProDOT-Bz₂/Pt) were used as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). The composite films were prepared on fluorine-doped tin oxide (FTO) glass by radio frequency (RF) sputtering to deposit platinum [...] Read more.

In this study, poly(3,3-dibenzyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine)/platinum composite films (PProDOT-Bz₂/Pt) were used as counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). The composite films were prepared on fluorine-doped tin oxide (FTO) glass by radio frequency (RF) sputtering to deposit platinum (Pt) for 30 s. Afterwards, PProDOT-Bz₂ was deposited on the Pt–FTO glass via electrochemical polymerization. The electron transfer process of DSSCs was investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The DSSCs with 0.05 C/cm² PProDOT-Bz₂-Pt composite films showed an open circuit voltage (V_oc) of 0.70 V, a short-circuit current density (J_sc) of 7.27 mA/cm², and a fill factor (F.F.) of 68.74%. This corresponded to a photovoltaic conversion efficiency (η) of 3.50% under a light intensity of 100 mW/cm². Full article

(This article belongs to the Special Issue Functionally Responsive Polymeric Materials)

▼ Show Figures

Graphical abstract

13 pages, 1833 KiB

Open AccessArticle

Novel Two-Dimensional Conjugated Polymer Containing Fluorinated Bithiophene as Donor and Benzoselenodiazole as Acceptor Units with Vinyl-Terthiophene Pendants for Polymer Photovoltaic Cells

by Rathinam Raja^1,*, Shengkai Luo^1,2, Chuen-Yo Hsiow¹, Syang-Peng Rwei²

and Leeyih Wang^1,3,*

¹ Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan

² Institute of Organic and Polymeric Materials, National Taipei University of Technology, Taipei 10608, Taiwan

³ Institute of Polymer Science and Engineering, National Taiwan University, Taipei 10617, Taiwan

Polymers 2017, 9(7), 272; https://doi.org/10.3390/polym9070272 - 7 Jul 2017

Cited by 5 | Viewed by 5730

Abstract

Novel two-dimensional conjugated copolymer, abbreviated as PDTBSeVTT-2TF, containing electron-deficient 4,7-di(thiophen-2-yl)benzo[c][1,2,5]selenodiazole (DTBSe) unit, conjugated vinyl-terthiophene (VTT) side chain and 3,3′-difluoro-2,2′-bithiophene (2TF) was designed and synthesized using microwave-assisted Stille cross-coupling polymerization. UV–visible absorption and cyclic voltammetry studies revealed that this copolymer possesses a [...] Read more.

Novel two-dimensional conjugated copolymer, abbreviated as PDTBSeVTT-2TF, containing electron-deficient 4,7-di(thiophen-2-yl)benzo[c][1,2,5]selenodiazole (DTBSe) unit, conjugated vinyl-terthiophene (VTT) side chain and 3,3′-difluoro-2,2′-bithiophene (2TF) was designed and synthesized using microwave-assisted Stille cross-coupling polymerization. UV–visible absorption and cyclic voltammetry studies revealed that this copolymer possesses a strong and broad absorption in the range of 300–800 nm and a narrow optical bandgap (E_g) of 1.57 eV with low-lying HOMO and LUMO energy levels. Further, the bulk heterojunction polymer solar cells (PSCs) were fabricated using PDTBSeVTT-2TF as donor and [6,6]-phenyl-C₇₁-butyric acid methyl ester (PC₇₁BM) as acceptor with an inverted device structure of ITO/ZnO/PDTBSeVTT-2TF:PC₇₁BM/V₂O₅/Ag. The processing temperature of blend solution for preparing PDTBSeVTT-2TF:PC₇₁BM active layer showed obvious impact on the photovoltaic performance of solar devices. The cell fabricated from the blend solution at 65 °C exhibited enhanced power conversion efficiencies (PCE) of 5.11% with a J_sc of 10.99 mA/cm⁻² compared with the one at 50 °C, which had a PCE of 4.69% with a J_sc of 10.10 mA/cm⁻². This enhancement is due to the dissolution of PDTBSeVTT-2TF clusters into single molecules and small aggregates, improving the miscibility between the polymer and PC₇₁BM and thus increasing the donor/acceptor interface. Full article

(This article belongs to the Special Issue Polymer Solar Cells)

▼ Show Figures

Graphical abstract

15 pages, 7194 KiB

Open AccessArticle

Effective Removal of Chromium(III) from Low Concentration Aqueous Solution Using a Novel Diazene/Methoxy-Laced Coordination Polymer

by Lei-Lei Liu^*, Yun Xing, Hui-Ying Yu, Cai-Wen Zhang, Meng-Qi Ye, Ming-Zhen Miao and Cai-Xia Yu^*

Henan Key Laboratory of New Optoelectronic Functional Materials, College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang 455000, China

Polymers 2017, 9(7), 273; https://doi.org/10.3390/polym9070273 - 9 Jul 2017

Cited by 9 | Viewed by 5460

Abstract

In this study, a novel coordination polymer [CdL₂(H₂O)_0.5]_n (1), [HL = 4-(2-(4-((pyridin-3-yl)methoxy)phenyl)diazenyl)benzoic acid] was fabricated via an in situ ligand transformation reaction under solvothermal conditions. The as-prepared polymer exhibited a selectivity and efficiency for [...] Read more.

In this study, a novel coordination polymer [CdL₂(H₂O)_0.5]_n (1), [HL = 4-(2-(4-((pyridin-3-yl)methoxy)phenyl)diazenyl)benzoic acid] was fabricated via an in situ ligand transformation reaction under solvothermal conditions. The as-prepared polymer exhibited a selectivity and efficiency for Cr(III) removal with a high uptake capacity of 106.13 mg·g⁻¹. Interestingly, even in the low concentration (0.02–0.20 ppm), it still performs a relatively high efficiency (≥ 92.5%) towards the removal of Cr(III) in aqueous solution. Remarkably, it also presents good selectivity and high efficiency (93.3%) for Cr(III) removal in the presences of interfering metal ions. The good removal performance for Cr(III) was demonstrated to be a structure-dependent chemical process between polymer and Cr(III) involving the diazene and methoxy groups in polymer 1, which happened not only on the surfaces of the adsorbent but also in the pores of polymer, giving rise to a strong affinity toward Cr(III) adsorption. The possible adsorption mechanism of Cr(III) was proposed and systematically verified by FT-IR, scanning electron microscope (SEM), atomic force microscope (AFM) and energy dispersive spectrometer (EDS) measurements. Full article

▼ Show Figures

Graphical abstract

13 pages, 2857 KiB

Open AccessArticle

A Rapid and Efficient Route to Preparation of Isocyanate Microcapsules

by Yangbao Ma, Yang Jiang, Haiyan Tan, Yanhua Zhang^* and Jiyou Gu^*

Material Science and Engineering College, Northeast Forestry University, Harbin 150040, China

Polymers 2017, 9(7), 274; https://doi.org/10.3390/polym9070274 - 9 Jul 2017

Cited by 27 | Viewed by 8559

Abstract

In this paper, polyaryl polymethylene isocyanates (PAPI) were used as an innovative alternative material to prepare isocyanate microcapsules. PAPI could be used as core materials, which would react with small molecules containing active hydrogen (1,4-butanediol, ethylene glycol, 1,2-diaminoethane etc.). The reaction products of [...] Read more.

In this paper, polyaryl polymethylene isocyanates (PAPI) were used as an innovative alternative material to prepare isocyanate microcapsules. PAPI could be used as core materials, which would react with small molecules containing active hydrogen (1,4-butanediol, ethylene glycol, 1,2-diaminoethane etc.). The reaction products of PAPI and active hydrogen would form a shell by interfacial polymerization reaction in an oil-in-water emulsion. Smooth spherical microcapsules of 70 ~ 180 μm in diameter were produced by controlling agitation rate (600 ~ 1200 rpm). High yields (~80%) of a free-flowing powder of PAPI/polyurethane and polyurea capsules were produced with a high isocyanate groups (–NCO) content of 23 wt % as determined by titration analysis. Structural analysis and quality assessments of each batch of microcapsules were performed by using thermogravimetric analysis, Fourier transform infrared spectroscopy and scanning electron microscopy. Preliminary results indicated the microcapsules were stable with only about 20% loss of –NCO detected after one month storage under ambient conditions. This work showed the great potential of novel microencapsulation technique in development of protection of –NCO and in aspects of micro- and nano-structure construction materials. Full article

▼ Show Figures

Figure 1

15 pages, 2901 KiB

Open AccessArticle

Structure of Amphiphilic Terpolymer Raspberry Vesicles

by Yingying Guo¹, Luca Di Mare^2,*, Robert K. Y. Li³ and Janet S. S. Wong^1,*

¹ Department of Mechanical Engineering, Imperial College London, London SW 7 2AZ, UK

² Department of Engineering Science, University of Oxford, Southwell Thermofluids Laboratory, Oxford OX2 OES, UK

³ Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong, China

Polymers 2017, 9(7), 275; https://doi.org/10.3390/polym9070275 - 9 Jul 2017

Cited by 5 | Viewed by 6798

Abstract

Terpolymer raspberry vesicles contain domains of different chemical affinities. They are potential candidates as multi-compartment cargo carriers. Their efficacy depends on their stability and load capacity. Using a model star terpolymer system in an aqueous solution, a dissipative particle dynamic (DPD) simulation is [...] Read more.

Terpolymer raspberry vesicles contain domains of different chemical affinities. They are potential candidates as multi-compartment cargo carriers. Their efficacy depends on their stability and load capacity. Using a model star terpolymer system in an aqueous solution, a dissipative particle dynamic (DPD) simulation is employed to investigate how equilibrium aggregate structures are affected by polymer concentration and pairwise interaction energy in a solution. It is shown that a critical mass of polymer is necessary for vesicle formation. The free energy of the equilibrium aggregates are calculated and the results show that the transition from micelles to vesicles is governed by the interactions between the longest solvophobic block and the solvent. In addition, the ability of vesicles to encapsulate solvent is assessed. It is found that reducing the interaction energy favours solvent encapsulation, although solvent molecules can permeate through the vesicle’s shell when repulsive interactions among monomers are low. Thus, one can optimize the loading capacity and the release rate of the vesicles by turning pairwise interaction energies of the polymer and the solvent. The ability to predict and control these aspects of the vesicles is an essential step towards designing vesicles for specific purposes. Full article

▼ Show Figures

Graphical abstract

7 pages, 3143 KiB

Open AccessArticle

Smart Poly(imidazoyl-l-lysine): Synthesis and Reversible Helix-to-Coil Transition at Neutral pH

by Estefania Piedra-Arroni^1,2, Fatma Makni^1,2, Laura Severac^1,2, Jean-Luc Stigliani^1,2, Geneviève Pratviel^1,2 and Colin Bonduelle^1,2,*

¹ CNRS, LCC (Laboratoire de Chimie de Coordination (UPR8241)), 205 route de Narbonne, F-31077 Toulouse 31400, France

² Université Paul Sabatier, Université de Toulouse, 118 Route de Narbonne, Toulouse 31062, France

Polymers 2017, 9(7), 276; https://doi.org/10.3390/polym9070276 - 11 Jul 2017

Cited by 13 | Viewed by 10276

Abstract

Polypeptide polymers can adopt natural protein secondary structures such as α-helices or β-sheets, and this unique feature is at the origin of some intriguing physico–chemical properties. In this work, we present how side chain imidazoylation of a poly(l-lysine) scaffold affords the [...] Read more.

Polypeptide polymers can adopt natural protein secondary structures such as α-helices or β-sheets, and this unique feature is at the origin of some intriguing physico–chemical properties. In this work, we present how side chain imidazoylation of a poly(l-lysine) scaffold affords the preparation of poly(histidine) counterparts exhibiting α-helix conformation. This structuring behavior is reversible and can be controlled by means of pH and or temperature changes. Full article

(This article belongs to the Special Issue Polypeptide Containing Polymers)

▼ Show Figures

Graphical abstract

16 pages, 3847 KiB

Open AccessArticle

Microporous Polyurethane Thin Layer as a Promising Scaffold for Tissue Engineering

by Justyna Kucińska-Lipka^1,*, Iga Gubanska¹ and Anna Skwarska²

¹ Department of Polymers Technology, Faculty of Chemistry, Gdansk University of Technology, Narutowicza St. 11/12, 80-233 Gdansk, Poland

² Department of Pharmaceutical Technology and Biochemistry, Faculty of Chemistry, Gdansk University of Technology, Narutowicza St. 11/12, 80-233 Gdansk, Poland

Polymers 2017, 9(7), 277; https://doi.org/10.3390/polym9070277 - 11 Jul 2017

Cited by 23 | Viewed by 7063

Abstract

The literature describes that the most efficient cell penetration takes place at 200–500 µm depth of the scaffold. Many different scaffold fabrication techniques were described to reach these guidelines. One such technique is solvent casting particulate leaching (SC/PL). The main advantage of this [...] Read more.

The literature describes that the most efficient cell penetration takes place at 200–500 µm depth of the scaffold. Many different scaffold fabrication techniques were described to reach these guidelines. One such technique is solvent casting particulate leaching (SC/PL). The main advantage of this technique is its simplicity and cost efficiency, while its main disadvantage is the scaffold thickness, which is usually not less than 3000 µm. Thus, the scaffold thickness is usually far from the requirements for functional tissue reconstruction. In this paper, we report a successful fabrication of the microporous polyurethane thin layer (MPTL) of 1 mm thick, which was produced using SC/PL technique combined with phase separation (PS). The obtained MPTL was highly porous (82%), had pore size in the range of 65–426 µm and scaffold average pore size was equal to 154 ± 3 µm. Thus, it can be considered a suitable scaffold for tissue engineering purpose, according to the morphology criterion. Polyurethane (PUR) processing into MPTL scaffold caused significant decrease of contact angle from 78 ± 4° to 56 ± 6° and obtained MPTL had suitable hydrophilic characteristic for mammalian cells growth and tissue regeneration. Mechanical properties of MPTL were comparable to the properties of native tissues. As evidenced by biotechnological examination the MPTL were highly biocompatible with no observed apparent toxicity on mouse embryonic NIH 3T3 fibroblast cells. Performed studies indicated that obtained MPTL may be suitable scaffold candidate for soft TE purposes such as blood vessels. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Biointerface)

▼ Show Figures

Figure 1

10 pages, 2999 KiB

Open AccessArticle

Modeling Diffractive Lenses Recording in Environmentally Friendly Photopolymer

by Roberto Fernández¹, Víctor Navarro-Fuster¹

, Francisco Javier Martínez^1,2

, Sergi Gallego^1,2,*

, Andrés Márquez^1,2

, Inmaculada Pascual¹

and Augusto Beléndez^1,2

¹ I.U. Física Aplicada a las Ciencias y las Tecnologías Universidad de Alicante, P.O. Box 99, E-03080 Alicante, Spain

² Departmento de Física, Ing. de Sistemas y Teoría de la Señal, Universidad de Alicante, P.O. Box 99, E-03080 Alicante, Spain

Polymers 2017, 9(7), 278; https://doi.org/10.3390/polym9070278 - 12 Jul 2017

Cited by 7 | Viewed by 5267

Abstract

The improvements made in diffusion models simulating phase image recording in photopolymers enable the optimization of a wide range of complex diffractive optical elements (DOEs), while the miniaturization of spatial light modulators makes it possible to generate both symmetric and non-symmetric DOEs. In [...] Read more.

The improvements made in diffusion models simulating phase image recording in photopolymers enable the optimization of a wide range of complex diffractive optical elements (DOEs), while the miniaturization of spatial light modulators makes it possible to generate both symmetric and non-symmetric DOEs. In addition, there is increasing interest in the design of new friendly recording materials. In this respect, photopolymers are a promising material due to their optical properties. In this paper, we show a procedure to record diffractive spherical lenses using a nontoxic optimized photopolymer. To achieve this goal, we followed three steps: first, the chemical optimization for DOE recording; second, the recording material characterization to be simulated by a three-dimensional diffusion model; and third, the evaluation of the coverplating for the conservation of the DOE. Full article

(This article belongs to the Special Issue Photo-Responsive Polymers)

▼ Show Figures

Figure 1

11 pages, 1782 KiB

Open AccessArticle

Hydrogenolysis and Activation of Soda Lignin Using [BMIM]Cl as a Catalyst and Solvent

by Shengming Zhang^1,2

, Liang Liu¹, Guizhen Fang^1,*, Ning Yan², Shixue Ren^1,* and Yanli Ma¹

¹ College of Material Science and Engineering, Northeast Forestry University, Harbin 150040, China

² Faculty of Forestry, Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON M5S 3B3, Canada

Polymers 2017, 9(7), 279; https://doi.org/10.3390/polym9070279 - 12 Jul 2017

Cited by 16 | Viewed by 5393

Abstract

To improve the reactivity of the soda lignin, an acid ionic liquid 1-butyl-3-mthylimidazolium chloride ([BMIM]Cl) was used as the catalyst and solvent to degrade the soda lignin through hydrogenolysis. Structural elucidation of the lignin samples was conducted by using a combination of analytical [...] Read more.

To improve the reactivity of the soda lignin, an acid ionic liquid 1-butyl-3-mthylimidazolium chloride ([BMIM]Cl) was used as the catalyst and solvent to degrade the soda lignin through hydrogenolysis. Structural elucidation of the lignin samples was conducted by using a combination of analytical methods including chemical analysis, ultraviolet spectrophotometry (UV spectrophotometry), Fourier transform infrared spectroscopy (FT-IR spectra), two-dimensional heteronuclear single quantum coherence nuclear magnetic resonance (2D-HSQC NMR) techniques, and gel permeation chromatography (GPC). The antioxidant activities of the lignin samples were evaluated using the diammonium 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS⁺) radical scavenging and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging methods. The degradation mechanism was proposed based on the characterization results. The optimal reaction condition was as follows: the concentration of [BMIM]Cl in the solution was 10 wt %, the hydrogen initial pressure was 3 MPa, and the solution was heated for 4 h at 90 °C. After the reaction, the total hydroxyl content of the soda lignin increased by 81.3%, while the phenolic hydroxyl content increased by 23.1%. At the same time, the weight-average molar mass of the soda lignin sample decreased from 8220 to 6450 g/mol with an improved antioxidant activity. In addition, approximately 56.7% of the β-O-4 linkages were degraded in the lreaction. The main effect of the acid ionic liquid [BMIM]C1 was related to the cleavage of β-O-4 linkages. This study has shown the potential of using the catalyzed soda lignin as a natural polymer antioxidant. Full article

▼ Show Figures

Figure 1

16 pages, 9601 KiB

Open AccessArticle

PES/POSS Soluble Veils as Advanced Modifiers for Multifunctional Fiber Reinforced Composites

by Gianluca Cicala^1,*

, Ignazio Blanco¹

, Alberta Latteri¹, Giulia Ognibene²

, Francesco Agatino Bottino² and Maria Elena Fragalà²

¹ Department of Civil Engineering and Architecture and INSTM UdR, University of Catania, V.le A. Doria 6, 95125 Catania, Italy

² Department of Chemical Science and INSTM UdR, University of Catania, V.le A. Doria 6, 95125 Catania, Italy

Polymers 2017, 9(7), 281; https://doi.org/10.3390/polym9070281 - 13 Jul 2017

Cited by 20 | Viewed by 6894

Abstract

Novel polyhedral oligomeric silsesquioxanes (POSS)-filled thermoplastic electrospun veils were used to tailor the properties of the interlaminar region of epoxy-based composites. The veils were designed to be soluble upon curing in the epoxy matrix, so that POSS could be released within the interlaminar [...] Read more.

Novel polyhedral oligomeric silsesquioxanes (POSS)-filled thermoplastic electrospun veils were used to tailor the properties of the interlaminar region of epoxy-based composites. The veils were designed to be soluble upon curing in the epoxy matrix, so that POSS could be released within the interlaminar region. Three different POSS contents, varying from 1 to 10 wt %, were tested while the percentage of coPolyethersulphone (coPES) dissolved in the epoxy resin was kept to a fixed value of 10 wt %. Good quality veils could be obtained at up to 10 wt % of POSS addition, with the nanofibers’ diameters varying from 861 nm for the coPES to 428 nm upon POSS addition. The feasibility of the soluble veils to disperse POSS in the interlaminar region was proved, and the effect of POSS on phase morphology and viscoelastic properties studied. POSS was demonstrated to significantly affect the morphology and viscoelastic properties of epoxy composites, especially for the percentages 1% and 5%, which enabled the composites to avoid POSS segregates occurring. A dynamic mechanical analysis showed a significant improvement to the storage modulus, and a shift of more than 30 °C due to the POSS cages hindering the motion of the molecular chains and network junctions. Full article

(This article belongs to the Special Issue Polymer Nanocomposites)

▼ Show Figures

Graphical abstract

21 pages, 4571 KiB

Open AccessFeature PaperArticle

“Living” Polymerization of Ethylene and 1-Hexene Using Novel Binuclear Pd–Diimine Catalysts

by Jianding Ye and Zhibin Ye^*

Bharti School of Engineering, Laurentian University, Sudbury, ON P3E 2C6, Canada

Polymers 2017, 9(7), 282; https://doi.org/10.3390/polym9070282 - 15 Jul 2017

Cited by 3 | Viewed by 8027

Abstract

We report the synthesis of two novel binuclear Pd–diimine catalysts and their unique behaviors in initiating “living” polymerization of ethylene and 1-hexene. These two binuclear catalysts, [(N^N)Pd(CH₂)₃C(O)O(CH₂)_mO(O)C(CH₂)₃Pd(N^N)](SbF₆)₂ ( [...] Read more.

We report the synthesis of two novel binuclear Pd–diimine catalysts and their unique behaviors in initiating “living” polymerization of ethylene and 1-hexene. These two binuclear catalysts, [(N^N)Pd(CH₂)₃C(O)O(CH₂)_mO(O)C(CH₂)₃Pd(N^N)](SbF₆)₂ (3a: m = 4, 3b: m = 6) (N^N≡ArN=C(Me)–(Me)C=NAr, Ar≡2,6–(iPr)₂C₆H₃), were synthesized by simply reacting [(N^N)Pd(CH₃)(N≡CMe)]SbF₆ (1) with diacrylates, 1,4-butanediol diacrylate and 1,6-hexanediol diacrylate, respectively. Their unique binuclear structure with two identical Pd–diimine acrylate chelates covalently linked together through an ester linkage was confirmed by NMR and single crystal XRD measurements. Ethylene “living” polymerizations were carried out at 5 °C and under ethylene pressure of 400 and 100 psi, respectively, with the binuclear catalysts, along with a mononuclear chelate catalyst, [(N^N)Pd(CH₂)₃C(O)OMe]SbF₆ (2), for comparison. All the polyethylenes produced with both binuclear catalysts show bimodal molecular weight distribution with the number-average molecular weight of the higher molecular weight portion being approximately twice that of the lower molecular weight portion. The results demonstrate the presence of monofunctional chain growing species resembling catalyst 2, in addition to the expected bifunctional species leading to bifunctional “living” polymerization, in the polymerization systems. Both types of chain growing species exhibit “living” characteristics under the studied conditions, leading to the simultaneous linear increase of molecular weight in both portions. However, when applied for the “living” polymerization of 1-hexene, the binuclear catalyst 3a leads to polymers with only monomodal molecular weight distribution, indicating the sole presence of monofunctional chain growing species. These two binuclear catalysts are the first Pd–diimine catalysts capable of initiating bifunctional ethylene “living” polymerization. Full article

(This article belongs to the Special Issue Tailored Polymer Synthesis by Advanced Polymerization Techniques)

▼ Show Figures

Figure 1

9 pages, 24576 KiB

Open AccessCommunication

Fabrication and Test of an Inflated Circular Diaphragm Dielectric Elastomer Generator Based on PDMS Rubber Composite

by Giacomo Moretti¹, Michele Righi¹, Rocco Vertechy² and Marco Fontana^3,*

¹ TeCIP Institute, Scuola Superiore Sant’Anna, P.zza dei Martiri, 33, 56127 Pisa, Italy

² Department of Industrial Engineering, University of Bologna, Viale del Risorgimento, 2, 40136 Bologna, Italy

³ Department of Industrial Engineering, University of Trento, Via Somarive, 9, 38123 Trento, Italy

Polymers 2017, 9(7), 283; https://doi.org/10.3390/polym9070283 - 15 Jul 2017

Cited by 44 | Viewed by 10099

Abstract

This paper introduces a fabrication method and the experimental characterization of a soft polymeric energy converter manufactured using a combination of dielectric and conductive polydimethylsiloxane elastomers. The presented system is an inflated circular diaphragm dielectric elastomer generator; i.e., a deformable electrostatic transducer that [...] Read more.

This paper introduces a fabrication method and the experimental characterization of a soft polymeric energy converter manufactured using a combination of dielectric and conductive polydimethylsiloxane elastomers. The presented system is an inflated circular diaphragm dielectric elastomer generator; i.e., a deformable electrostatic transducer that converts the mechanical work done by a time-varying pressure into electricity. A prototype of the system is realized on the basis of a simple fabrication procedure that makes use of commercially available silicone dielectric elastomer films and custom-prepared deformable conductive electrodes. A test-bench is developed and employed to estimate the energy conversion performance. Remarkable results are obtained, such as an amount of energy converted per cycle of up to 0.3 J, converted power of up to 0.15 W, energy per unit of employed elastomer mass of up to 173 J/kg, and fraction of the input mechanical work converted into electricity of 30%. Full article

(This article belongs to the Special Issue Electroactive Polymers and Gels)

▼ Show Figures

Graphical abstract

18 pages, 8598 KiB

Open AccessArticle

Three Carbazole-Based Polymers as Potential Anodically Coloring Materials for High-Contrast Electrochromic Devices

by Yuh-Shan Su and Tzi-Yi Wu^*

Department of Chemical and Materials Engineering, National Yunlin University of Science and Technology, Yunlin 64002, Taiwan

Polymers 2017, 9(7), 284; https://doi.org/10.3390/polym9070284 - 18 Jul 2017

Cited by 30 | Viewed by 6475

Abstract

Three carbazole-based conjugated polymers (poly(3,6-di(2-thienyl)carbazole) (PDTC), poly(2,7-bis(carbazol-9-yl)-9,9-spirobifluorene) (PS2CBP), and poly(3,6-bis(N-carbazole)-N-ethylcarbazole) (PCEC)) are synthesized using electrochemical polymerization. The spectroelectrochemical studies indicate that the PDTC, PS2CBP, and PCEC films show reversible electrochromic behaviors in their redox states, and the PS2CBP film [...] Read more.

Three carbazole-based conjugated polymers (poly(3,6-di(2-thienyl)carbazole) (PDTC), poly(2,7-bis(carbazol-9-yl)-9,9-spirobifluorene) (PS2CBP), and poly(3,6-bis(N-carbazole)-N-ethylcarbazole) (PCEC)) are synthesized using electrochemical polymerization. The spectroelectrochemical studies indicate that the PDTC, PS2CBP, and PCEC films show reversible electrochromic behaviors in their redox states, and the PS2CBP film shows a distinct color transition with four various colors (gray at 0 V, grayish-green at 1.0 V, moss green at 1.2 V, and foliage green at 1.4 V). The maximum optical contrast of the PS2CBP and PCEC films is 39.83% at 428 nm and 32.41% at 420 nm, respectively, in an ionic liquid solution. Dual-type electrochromic devices (ECDs) that employ PDTC, PS2CBP, or PCEC film as an anodic layer, and PProDOT-Et₂ film as a cathodic layer, were constructed. The as-prepared PCEC/PProDOT-Et₂ ECD shows high optical contrast (38.25% at 586 nm) and high coloration efficiency (369.85 cm² C⁻¹ at 586 nm), and the PS2CBP/PProDOT-Et₂ ECD shows high optical contrast (34.45% at 590 nm), good optical memory, and good long-term cycling stability. Full article

(This article belongs to the Special Issue Polymeric Materials for Optical Applications)

▼ Show Figures

Graphical abstract

10 pages, 2102 KiB

Open AccessArticle

Dependency of Anion and Chain Length of Imidazolium Based Ionic Liquid on Micellization of the Block Copolymer F127 in Aqueous Solution: An Experimental Deep Insight

by Jignesh Lunagariya^1,†, Nadavala Siva Kumar^2,*,†, Mohammad Asif², Abhishek Dhar³ and Rohit L. Vekariya^4,5,*,†

¹ Department of Chemistry, College of Chemistry and Materials Science, Jinan University, Guangzhou 510632, China

² Department of Chemical Engineering, King Saud University, P.O. Box 800, Riyadh 11421, Saudi Arabia

³ Department of Science & Technology, Government of West Bengal, 26/B, Block-DD, Sector-I, Salt Lake, Kolkata 700064, India

⁴ Department for Management of Science and Technology Development, Ton Duc Thang University, Ho Chi Minh City, Vietnam

⁵ Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Vietnam

^† These authors contribute equally to this work.

Polymers 2017, 9(7), 285; https://doi.org/10.3390/polym9070285 - 19 Jul 2017

Cited by 18 | Viewed by 7928

Abstract

The non-ionic triblock copolymer, Pluronic^® F127, has been selected to observe its interaction with ionic liquids (ILs) in aqueous solutions by using DLS, surface tension, and viscosity measurements. The Critical Micelle Concentration (CMC) of F127 increased with the addition of ILs, which [...] Read more.

The non-ionic triblock copolymer, Pluronic^® F127, has been selected to observe its interaction with ionic liquids (ILs) in aqueous solutions by using DLS, surface tension, and viscosity measurements. The Critical Micelle Concentration (CMC) of F127 increased with the addition of ILs, which appeared logical since it increases the solubility of PPO (and PEO) moiety, making it behaves more like a hydrophilic block copolymer that is micellized at a higher copolymer concentration. The results from DLS data showed good agreement with those obtained from the surface tension measurements. Upon the addition of ILs, the tendency in micellar size reduction was demonstrated by viscosity results, and therefore, intrinsic viscosity decreased compared to pure F127 in aqueous solution. The results were discussed as a function of alkyl chain length and anions of imidazolium based ILs. Full article

▼ Show Figures

Figure 1

29 pages, 9475 KiB

Open AccessArticle

Effect of Drug Loading Method and Drug Physicochemical Properties on the Material and Drug Release Properties of Poly (Ethylene Oxide) Hydrogels for Transdermal Delivery

by Rachel Shet Hui Wong and Kalliopi Dodou^*

School of Pharmacy and Pharmaceutical Sciences, Faculty of Health Sciences and Wellbeing,University of Sunderland, Science Complex, Wharncliffe Street, Sunderland SR1 3SD, UK

Polymers 2017, 9(7), 286; https://doi.org/10.3390/polym9070286 - 19 Jul 2017

Cited by 66 | Viewed by 9703

Abstract

Novel poly (ethylene oxide) (PEO) hydrogel films were synthesized via UV cross-linking with pentaerythritol tetra-acrylate (PETRA) as cross-linking agent. The purpose of this work was to develop a novel hydrogel film suitable for passive transdermal drug delivery via skin application. Hydrogels were loaded [...] Read more.

Novel poly (ethylene oxide) (PEO) hydrogel films were synthesized via UV cross-linking with pentaerythritol tetra-acrylate (PETRA) as cross-linking agent. The purpose of this work was to develop a novel hydrogel film suitable for passive transdermal drug delivery via skin application. Hydrogels were loaded with model drugs (lidocaine hydrochloride (LID), diclofenac sodium (DIC) and ibuprofen (IBU)) via post-loading and in situ loading methods. The effect of loading method and drug physicochemical properties on the material and drug release properties of medicated film samples were characterized using scanning electron microscopy (SEM), swelling studies, differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FT-IR), tensile testing, rheometry, and drug release studies. In situ loaded films showed better drug entrapment within the hydrogel network and also better polymer crystallinity. High drug release was observed from all studied formulations. In situ loaded LID had a plasticizing effect on PEO hydrogel, and films showed excellent mechanical properties and prolonged drug release. The drug release mechanism for the majority of medicated PEO hydrogel formulations was determined as both drug diffusion and polymer chain relaxation, which is highly desirable for controlled release formulations. Full article

▼ Show Figures

Graphical abstract

11 pages, 4631 KiB

Open AccessArticle

A New Type of Photo-Thermo Staged-Responsive Shape-Memory Polyurethanes Network

by Jinghao Yang¹, Hao Wen¹, Haitao Zhuo², Shaojun Chen^1,* and Jianfeng Ban^1,*

¹ Guangdong Research Center for Interfacial Engineering of Functional Materials, Shenzhen Key Laboratory of Polymer Science and Technology, Nanshan District Key Lab for Biopolymers and Safety Evaluation, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, China

² Shenzhen Key Laboratory of Functional Polymer, College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, 518060, China

Polymers 2017, 9(7), 287; https://doi.org/10.3390/polym9070287 - 19 Jul 2017

Cited by 25 | Viewed by 6324

Abstract

In this paper, we developed a photo-thermo staged-responsive shape-memory polymer network which has a unique ability of being spontaneously photo-responsive deformable and thermo-responsive shape recovery. This new type of shape-memory polyurethane network (A-SMPUs) was successfully synthesized with 4,4-azodibenzoic acid (Azoa), hexamethylenediisocyanate (HDI) and [...] Read more.

In this paper, we developed a photo-thermo staged-responsive shape-memory polymer network which has a unique ability of being spontaneously photo-responsive deformable and thermo-responsive shape recovery. This new type of shape-memory polyurethane network (A-SMPUs) was successfully synthesized with 4,4-azodibenzoic acid (Azoa), hexamethylenediisocyanate (HDI) and polycaprolactone (PCL), followed by chemical cross-linking with glycerol (Gl). The structures, morphology, and shape-memory properties of A-SMPUs have been carefully investigated. The results demonstrate that the A-SMPUs form micro-phase separation structures consisting of a semi-crystallized PCL soft phase and an Azoa amorphous hard phase that could influence the crystallinity of PCL soft phases. The chemical cross-linking provided a stable network and good thermal stability to the A-SMPUs. All A-SMPUs exhibited good triple-shape-memory properties with higher than 97% shape fixity ratio and 95% shape recovery ratio. Additionally, the A-SMPUs with higher Azoa content exhibited interesting photo-thermo two-staged responsiveness. A pre-processed film with orientated Azoa structure exhibited spontaneous curling deformation upon exposing to ultraviolet (UV) light, and curling deformation is constant even under Vis light. Finally, the curling deformation can spontaneously recover to the original shape by applying a thermal stimulus. This work demonstrates new synergistically multi-responsive SMPUs that will have many applications in smart science and technology. Full article

(This article belongs to the Special Issue Shape Memory Polymers)

▼ Show Figures

Graphical abstract

14 pages, 3588 KiB

Open AccessArticle

Ultra High Electrical Performance of Nano Nickel Oxide and Polyaniline Composite Materials

by Xiaomin Cai^1,2, Xiuguo Cui^1,*, Lei Zu^1,2, You Zhang^1,2, Xing Gao^1,2, Huiqin Lian^3,*, Yang Liu¹ and Xiaodong Wang²

¹ College of Material Science and Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617, China

² State Key Laboratory of Organic–Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China

³ Beijing Key Laboratory of Specialty Elastomer Composite Materials, Beijing Institute of Petrochemical Technology, Beijing 102617, China

Polymers 2017, 9(7), 288; https://doi.org/10.3390/polym9070288 - 20 Jul 2017

Cited by 36 | Viewed by 8086

Abstract

The cooperative effects between the PANI (polyaniline)/nano-NiO (nano nickel oxide) composite electrode material and redox electrolytes (potassium iodide, KI) for supercapacitor applications was firstly discussed in this article, providing a novel method to prepare nano-NiO by using β-cyelodextrin (β-CD) as the template agent. [...] Read more.

The cooperative effects between the PANI (polyaniline)/nano-NiO (nano nickel oxide) composite electrode material and redox electrolytes (potassium iodide, KI) for supercapacitor applications was firstly discussed in this article, providing a novel method to prepare nano-NiO by using β-cyelodextrin (β-CD) as the template agent. The experimental results revealed that the composite electrode processed a high specific capacitance (2122.75 F·g⁻¹ at 0.1 A·g⁻¹ in 0.05 M KI electrolyte solution), superior energy density (64.05 Wh·kg⁻¹ at 0.2 A·g⁻¹ in the two-electrode system) and excellent cycle performance (86% capacitance retention after 1000 cycles at 1.5 A·g⁻¹). All those ultra-high electrical performances owe to the KI active material in the electrolyte and the PANI coated nano-NiO structure. Full article

▼ Show Figures

Figure 1

14 pages, 1540 KiB

Open AccessArticle

Effect of Plasticizer Type on Tensile Property and In Vitro Indomethacin Release of Thin Films Based on Low-Methoxyl Pectin

by Pensak Jantrawut^1,*

, Tanpong Chaiwarit¹, Kittisak Jantanasakulwong², Claire Hélène Brachais³ and Odile Chambin⁴

¹ Department of Pharmaceutical Sciences, Faculty of Pharmacy, Chiang Mai University, Chiang Mai 50200, Thailand

² School of Agro-Industry, Faculty of Agro-Industry, Chiang Mai University, Chiang Mai 50100, Thailand

³ ICMUB UMR CNRS 6302, University of Bourgogne Franche-Comté, 9 Avenue Alain Savary, Dijon 21000, France

⁴ Department of Pharmaceutical Technology, UMR PAM, Agrosup-University of Bourgogne Franche-Comté, 7 bd Jeanne d’Arc, Dijon 21079, France

Polymers 2017, 9(7), 289; https://doi.org/10.3390/polym9070289 - 20 Jul 2017

Cited by 107 | Viewed by 9535

Abstract

This study developed the interests of low-methoxyl pectin (LMP) together with plasticizers for the preparation of elastic thin films. The effect of different plasticizer types (glycerol: Gly; sorbitol: Sor; propylene glycol: PG; and polyethylene glycol 300: PEG 300) and concentrations (20–40% w/w) [...] Read more.

This study developed the interests of low-methoxyl pectin (LMP) together with plasticizers for the preparation of elastic thin films. The effect of different plasticizer types (glycerol: Gly; sorbitol: Sor; propylene glycol: PG; and polyethylene glycol 300: PEG 300) and concentrations (20–40% w/w) on mechanical and thermal properties of LMP films as well as on in vitro release of indomethacin were evaluated. Without any plasticizer, a brittle LMP film with low tensile strength and % elongation at break was obtained. Addition of plasticizers from 20% to 40% caused reduction in the tensile strength and Young’s modulus values, whereas percent elongation was increased. Forty percent Gly-plasticized and PG-plasticized films were selected to deliver indomethacin in comparison with non-plasticized film. No significant difference in indomethacin release profiles was displayed between the films. The analysis of indomethacin release model indicated that more than one drug release mechanism from the film formulation was involved and possibly the combination of both diffusion and erosion. Even though indomethacin incorporated in non-plasticized film showed similar release profile, Gly or PG should be added to enhanced film flexibility and decrease film brittleness. Full article

(This article belongs to the Collection Polysaccharides)

▼ Show Figures

Graphical abstract

14 pages, 3229 KiB

Open AccessArticle

Polymerizable Ionic Liquid Crystals Comprising Polyoxometalate Clusters toward Inorganic-Organic Hybrid Solid Electrolytes

by Takeru Ito^1,*

, Saki Otobe¹, Tatsuma Oda², Tatsuhiro Kojima^3,4, Seiji Ono², Masayuki Watanabe², Yoshiki Kiyota¹, Toshiyuki Misawa¹, Shinichi Koguchi¹, Masashi Higuchi², Masaki Kawano^3,5 and Yu Nagase^2,*

¹ Department of Chemistry, School of Science, Tokai University, 4-1-1 Kitakaname, Hiratsuka 259-1292, Japan

² Department of Applied Chemistry, School of Engineering, Tokai University, Hiratsuka, Kanagawa 259-1292, Japan

³ Division of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Korea

⁴ Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan

⁵ Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan

Polymers 2017, 9(7), 290; https://doi.org/10.3390/polym9070290 - 20 Jul 2017

Cited by 25 | Viewed by 8795

Abstract

Solid electrolytes are crucial materials for lithium-ion or fuel-cell battery technology due to their structural stability and easiness for handling. Emergence of high conductivity in solid electrolytes requires precise control of the composition and structure. A promising strategy toward highly-conductive solid electrolytes is [...] Read more.

Solid electrolytes are crucial materials for lithium-ion or fuel-cell battery technology due to their structural stability and easiness for handling. Emergence of high conductivity in solid electrolytes requires precise control of the composition and structure. A promising strategy toward highly-conductive solid electrolytes is employing a thermally-stable inorganic component and a structurally-flexible organic moiety to construct inorganic-organic hybrid materials. Ionic liquids as the organic component will be advantageous for the emergence of high conductivity, and polyoxometalate, such as heteropolyacids, are well-known as inorganic proton conductors. Here, newly-designed ionic liquid imidazolium cations, having a polymerizable methacryl group (denoted as MAImC₁), were successfully hybridized with heteropolyanions of [PW₁₂O₄₀]³⁻ (PW₁₂) to form inorganic-organic hybrid monomers of MAImC₁-PW₁₂. The synthetic procedure of MAImC₁-PW₁₂ was a simple ion-exchange reaction, being generally applicable to several polyoxometalates, in principle. MAImC₁-PW₁₂ was obtained as single crystals, and its molecular and crystal structures were clearly revealed. Additionally, the hybrid monomer of MAImC₁-PW₁₂ was polymerized by a radical polymerization using AIBN as an initiator. Some of the resulting inorganic-organic hybrid polymers exhibited conductivity of 10⁻⁴ S·cm⁻¹ order under humidified conditions at 313 K. Full article

(This article belongs to the Special Issue Conductive Polymers 2017)

▼ Show Figures

Figure 1

10 pages, 2541 KiB

Open AccessArticle

Electronically Stabilized Copoly(Styrene-Acrylic Acid) Submicrocapsules Prepared by Miniemulsion Copolymerization

by Minkwan Kim, Yura Hwang and Han Do Ghim^*

Department of Textile System Engineering, Kyungpook National University, 80 Daehakro, Bukgu, Daegu 41566, Korea

Polymers 2017, 9(7), 291; https://doi.org/10.3390/polym9070291 - 20 Jul 2017

Cited by 6 | Viewed by 5448

Abstract

This work reports the preparation and characterization of poly(styrene-acrylic acid) (St/AA) submicrocapsules by using the miniemulsion copolymerization method. AA was introduced to miniemulsion polymerization of St to increase the zeta potential and the resulting electrostatic stability of St/AA submicrocapsules. Phytoncide oil was adopted [...] Read more.

This work reports the preparation and characterization of poly(styrene-acrylic acid) (St/AA) submicrocapsules by using the miniemulsion copolymerization method. AA was introduced to miniemulsion polymerization of St to increase the zeta potential and the resulting electrostatic stability of St/AA submicrocapsules. Phytoncide oil was adopted as the core model material. Miniemulsion copolymerization of St and AA was conducted at a fixed monomer concentration (0.172 mol) with a varying monomer feed ratio [AA]/[St] (0.2, 0.25, 0.33, 0.5, and 1.0). Concentrations of initiator (azobisisobutyronitrile; 1.0 × 10⁻³, 2.0 × 10⁻³, 3.0 × 10⁻³, and 4.0 × 10⁻³ mol/mol of monomer) and surfactant (sodium dodecyl sulfate; 0.6 × 10⁻³, 1.0 × 10⁻³, and 1.4 × 10⁻³ mol) were also controlled to optimize the miniemulsion copolymerization of St and AA. Dynamic light scattering and microscopic analyses confirmed the optimum condition of miniemulsion copolymerization of St and AA. Long-term colloidal stability of aqueous St/AA submicrocapsule suspension was evaluated by using Turbiscan^TM Lab. In this work, the optimum condition for miniemulsion copolymerization of St and AA was determined ([AA]/[St] = 0.33; [SDS] = 1.0 × 10⁻³ mol; [AIBN] = 2.0 × 10⁻³ mol/mol of monomer). St/AA submicrocapsules prepared at the optimum condition (392.6 nm and −55.2 mV of mean particle size and zeta potential, respectively) showed almost no variations in backscattering intensity (stable colloids without aggregation). Full article

(This article belongs to the Special Issue Emulsion Polymerization)

▼ Show Figures

Graphical abstract

17 pages, 20796 KiB

Open AccessArticle

Preparation of Fluoroalkyl End-Capped Vinyltrimethoxysilane Oligomeric Silica Nanocomposites Containing Gluconamide Units Possessing Highly Oleophobic/Superhydrophobic, Highly Oleophobic/Superhydrophilic, and Superoleophilic/Superhydrophobic Characteristics on the Modified Surfaces

by Shinsuke Katayama^1,2, Shogo Fujii¹, Tomoya Saito¹, Shohei Yamazaki¹ and Hideo Sawada^1,*

¹ Department of Frontier Materials Chemistry, Graduate School of Science and Technology, Hirosaki University, Hirosaki 036-8561, Japan

² Production Engineering Department, Kanto Denka Kogyo Co., Ltd., Kurashiki 712-8533, Japan

Polymers 2017, 9(7), 292; https://doi.org/10.3390/polym9070292 - 20 Jul 2017

Cited by 5 | Viewed by 5809

Abstract

Fluoroalkyl end-capped vinyltrimethoxysilane oligomer [R_F-(CH₂-CHSi(OMe)₃)_n-R_F (R_F-(VM)_n-R_F)] undergoes the sol-gel reaction in the presence of N-(3-triethoxysilylpropyl)gluconamide [Glu-Si(OEt)₃] under alkaline conditions to afford the corresponding fluorinated oligomeric [...] Read more.

Fluoroalkyl end-capped vinyltrimethoxysilane oligomer [R_F-(CH₂-CHSi(OMe)₃)_n-R_F (R_F-(VM)_n-R_F)] undergoes the sol-gel reaction in the presence of N-(3-triethoxysilylpropyl)gluconamide [Glu-Si(OEt)₃] under alkaline conditions to afford the corresponding fluorinated oligomeric silica nanocomposites containing gluconamide units [R_F-(VM-SiO_3/2)_n-R_F/Glu-SiO_3/2]. These obtained nanocomposites were applied to the surface modification of glass to provide the unique wettability characteristics such as highly oleophobic/superhydrophobic and highly oleophobic/superhydrophilic on the modified surfaces under a variety of conditions. Such a highly oleophobic/superhydrophobic characteristic was also observed on the modified PET (polyethylene terephthalate) fabric swatch, which was prepared under similar conditions, and this modified PET fabric swatch was applied to the separation membrane for the separation of the mixture of fluorocarbon oil and hydrocarbon oil. The R_F-(VM-SiO_3/2)_n-R_F/Glu-SiO_3/2 nanocomposites, which were prepared under lower feed amounts of basic catalyst (ammonia), were found to cause gelation in water. Interestingly, it was demonstrated that these gelling nanocomposites are also applied to the surface modification of the PET fabric swatch to give a highly oleophobic/superhydrophobic characteristic on the surface. On the other hand, the modified glass surfaces treated with the corresponding nanocomposite possessing no gelling ability were found to supply the usual hydrophobic characteristic with a highly oleophobic property. More interestingly, the wettability change on the modified PET fabric swatch from highly oleophobic to superoleophilic was observed, and remained superhydrophobic after immersing the modified PET fabric swatch into water. Full article

(This article belongs to the Special Issue Fluorinated Polymers)

▼ Show Figures

Graphical abstract

15 pages, 2974 KiB

Open AccessArticle

Self-Assembly of Double Hydrophilic Poly(2-ethyl-2-oxazoline)-b-poly(N-vinylpyrrolidone) Block Copolymers in Aqueous Solution

by Jochen Willersinn and Bernhard V.K.J. Schmidt^*

Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany

Polymers 2017, 9(7), 293; https://doi.org/10.3390/polym9070293 - 20 Jul 2017

Cited by 26 | Viewed by 7448

Abstract

The self-assembly of a novel combination of hydrophilic blocks in water is presented, namely poly(2-ethyl-2-oxazoline)-b-poly(N-vinylpyrrolidone) (PEtOx-b-PVP). The completely water-soluble double hydrophilic block copolymer (DHBC) is formed via copper-catalyzed polymer conjugation, whereas the molecular weight of the PVP [...] Read more.

The self-assembly of a novel combination of hydrophilic blocks in water is presented, namely poly(2-ethyl-2-oxazoline)-b-poly(N-vinylpyrrolidone) (PEtOx-b-PVP). The completely water-soluble double hydrophilic block copolymer (DHBC) is formed via copper-catalyzed polymer conjugation, whereas the molecular weight of the PVP is varied in order to study the effect of block ratio on the self-assembly process. Studies via dynamic light scattering, static light scattering as well as microscopy techniques, e.g., cryo scanning electron microscopy or laser scanning confocal microscopy, show the formation of spherical particles in an aqueous solution with sizes between 300 and 400 nm. Particles of the DHBCs are formed without the influence of external stimuli. Moreover, the efficiency of self-assembly formation relies significantly on the molar ratio of the utilized blocks. The nature of the formed structures relies further on the concentration, and indications of particular and vesicular structures are found. Full article

(This article belongs to the Special Issue Polymers and Block Copolymers at Interfaces and Surfaces)

▼ Show Figures

Graphical abstract

14 pages, 2362 KiB

Open AccessArticle

Gas Barrier, Thermal, Mechanical and Rheological Properties of Highly Aligned Graphene-LDPE Nanocomposites

by Karolina Gaska^1,*, Roland Kádár²

, Andrzej Rybak³

, Artur Siwek³ and Stanislaw Gubanski¹

¹ Department of Electrical Engineering, Chalmers University of Technology, 41296 Gothenburg, Sweden

² Department of Industrial and Materials Science, Chalmers University of Technology, 41296 Gothenburg, Sweden

³ ABB Corporate Research Center, 31038 Krakow, Poland

Polymers 2017, 9(7), 294; https://doi.org/10.3390/polym9070294 - 21 Jul 2017

Cited by 71 | Viewed by 10650

Abstract

This contribution reports on properties of low-density polyethylene-based composites filled with different amounts of graphene nanoplatelets. The studied samples were prepared in the form of films by means of the precoating technique and single screw melt-extrusion, which yields a highly ordered arrangement of [...] Read more.

This contribution reports on properties of low-density polyethylene-based composites filled with different amounts of graphene nanoplatelets. The studied samples were prepared in the form of films by means of the precoating technique and single screw melt-extrusion, which yields a highly ordered arrangement of graphene flakes and results in a strong anisotropy of composites morphology. The performed tests of gas permeability reveal a drastic decrease of this property with increasing filler content. A clear correlation is found between permeability and free volume fraction in the material, the latter evaluated by means of positron annihilation spectroscopy. A strong anisotropy of the thermal conductivity is also achieved and the thermal conductivity along the extrusion direction for samples filled with 7.5 wt % of GnP (graphene nanoplatelets) reached 2.2 W/m·K. At the same time, when measured through a plane, a slight decrease of thermal conductivity is found. The use of GnP filler leads also to improvements of mechanical properties. The increase of Young’s modulus and tensile strength are reached as the composites become more brittle. Full article

▼ Show Figures

Graphical abstract

9 pages, 4493 KiB

Open AccessArticle

Light-Driven Rotation and Pitch Tuning of Self-Organized Cholesteric Gratings Formed in a Semi-Free Film

by Ling-Ling Ma¹, Wei Duan¹, Ming-Jie Tang¹, Lu-Jian Chen², Xiao Liang³, Yan-Qing Lu¹ and Wei Hu^1,*

¹ National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures and College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China

² Department of Electronic Engineering, School of Information Science and Engineering, Xiamen University, Xiamen 361005, China

³ Department of Chemistry, Tsinghua University, Beijing 100084, China

Polymers 2017, 9(7), 295; https://doi.org/10.3390/polym9070295 - 21 Jul 2017

Cited by 29 | Viewed by 7679

Abstract

Cholesteric liquid crystal (CLC) has attracted intensive attention due to its ability to form a periodic helical structure with broad tunability. CLC gratings in open systems are especially promising in sensing and micromanipulation. However, there is still much to learn about the inherent [...] Read more.

Cholesteric liquid crystal (CLC) has attracted intensive attention due to its ability to form a periodic helical structure with broad tunability. CLC gratings in open systems are especially promising in sensing and micromanipulation. However, there is still much to learn about the inherent mechanism of such gratings. We investigate the light-driven rotation and pitch-tuning behaviors of CLC gratings in semi-free films which are formed by spin-coating the CLC mixtures onto planarly photoaligned substrates. The doped azobenzene chiral molecular switch supplies great flexibility to realize the continuous grating rotation. The maximum continuous rotational angle reaches 987.8°. Moreover, dependencies of light-driven rotation and pitch tuning on the dopant concentration and exposure are studied. The model of director configuration in the semi-free film is constructed. Precise beam steering and synchronous micromanipulation are also demonstrated. Our work may provide new opportunities for the CLC grating in applications of beam steering, micromanipulation, and sensing. Full article

(This article belongs to the Special Issue Photo-Responsive Polymers)

▼ Show Figures

Graphical abstract

12 pages, 6723 KiB

Open AccessArticle

Design and Study of a Novel Thermal-Resistant and Shear-Stable Amphoteric Polyacrylamide in High-Salinity Solution

by Caili Dai^*, Zhongliang Xu, Yining Wu

, Chenwei Zou, Xuepeng Wu, Tao Wang, Xu Guo and Mingwei Zhao^*

School of Petroleum Engineering, State Key Laboratory of Heavy Oil Processing, China University of Petroleum (East China), Qingdao 266580, China

Polymers 2017, 9(7), 296; https://doi.org/10.3390/polym9070296 - 21 Jul 2017

Cited by 40 | Viewed by 6919

Abstract

Abstract: Water-soluble polymers are widely used in oilfields. The rheological behaviors of these polymers in high-salinity solution are very important for stimulation of high-salinity reservoirs. In this work, a novel thermal-resistant and shear-stable amphoteric polyacrylamide (PASD), prepared from acrylamide (AM), sodium styrene [...] Read more.

Abstract: Water-soluble polymers are widely used in oilfields. The rheological behaviors of these polymers in high-salinity solution are very important for stimulation of high-salinity reservoirs. In this work, a novel thermal-resistant and shear-stable amphoteric polyacrylamide (PASD), prepared from acrylamide (AM), sodium styrene sulfonate (SSS), and acryloxyethyl trimethylammonium chloride (DAC) monomers, was prepared by free-radical polymerization in high-salinity solution. The amphoteric polyacrylamide was characterized by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance spectroscopy (¹H NMR), elemental analysis, thermogravimetric analysis (TG), and scanning electron microscopy (SEM). The amphoteric polyacrylamide exhibited excellent salinity tolerance. The slow increase in apparent viscosity of the polymer with increase in salinity was interesting. The amphoteric polyacrylamide showed perfect temperature resistance in high-salinity solution. The viscosity retention reached 38.9% at 120 °C and was restored to 87.8% of its initial viscosity when temperature was decreased to room temperature. The retention ratio of apparent viscosity reached 49.7% at 170 s⁻¹ and could still retain it at 25.8% at 1000 s⁻¹. All these results demonstrated that PASD had excellent thermal-resistance and shear-stability in high-salinity solution. We expect that this work could provide a new strategy to design polymers with excellent salinity-tolerance, thermal-resistance, and shear-stability performances. Full article

▼ Show Figures

Figure 1

13 pages, 4232 KiB

Open AccessArticle

Biphasic Calcium Phosphate (BCP)-Immobilized Porous Poly (d,l-Lactic-co-Glycolic Acid) Microspheres Enhance Osteogenic Activities of Osteoblasts

by Kyu-Sik Shim^1,2,†, Sung Eun Kim^2,†, Young-Pil Yun², Somang Choi^1,2, Hak-Jun Kim², Kyeongsoon Park^3,*

and Hae-Ryong Song^2,*

¹ Department of Biomedical Science, College of Medicine, Korea University, Anam-dong, Seongbuk-gu, Seoul 02841, Korea

² Department of Orthopedic Surgery and Rare Diseases Institute, Korea University Medical College, Guro Hospital, #80, Guro-dong, Guro-gu, Seoul 08308, Korea

³ Department of Systems Biotechnology, College of Biotechnology and Natural Resources, Chung-Ang University, 4726 Seodong-daero, Daedeok-myeon, Anseong-si, Gyeonggi-do 17546, Korea

^† These authors contributed equally to this work.

Polymers 2017, 9(7), 297; https://doi.org/10.3390/polym9070297 - 21 Jul 2017

Cited by 7 | Viewed by 7900

Abstract

The purpose of this study was to evaluate the potential of porous poly (d,l-lactic-co-glycolic acid) (PLGA) microspheres (PMSs) immobilized on biphasic calcium phosphate nanoparticles (BCP NPs) (BCP-IM-PMSs) to enhance osteogenic activity. PMSs were fabricated using a fluidic device, and their surfaces [...] Read more.

The purpose of this study was to evaluate the potential of porous poly (d,l-lactic-co-glycolic acid) (PLGA) microspheres (PMSs) immobilized on biphasic calcium phosphate nanoparticles (BCP NPs) (BCP-IM-PMSs) to enhance osteogenic activity. PMSs were fabricated using a fluidic device, and their surfaces were modified with l-lysine (aminated-PMSs), whereas the BCP NPs were modified with heparin–dopamine (Hep-DOPA) to obtain heparinized–BCP (Hep-BCP) NPs. BCP-IM-PMSs were fabricated via electrostatic interactions between the Hep-BCP NPs and aminated-PMSs. The fabricated BCP-IM-PMSs showed an interconnected pore structure. In vitro studies showed that MG-63 cells cultured on BCP-IM-PMSs had increased alkaline phosphatase activity, calcium content, and mRNA expression of osteocalcin (OCN) and osteopontin (OPN) compared with cells cultured on PMSs. These data suggest that BCP NP-immobilized PMSs have the potential to enhance osteogenic activity. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Cell Scaffolds)

▼ Show Figures

Figure 1

12 pages, 2331 KiB

Open AccessArticle

Additives Type Schiff’s Base as Modifiers of the Optical Response in Holographic Polymer-Dispersed Liquid Crystals

by Sandra Fenoll^1,2, Víctor Navarro-Fuster^1,3

, Manuel Ortuño^1,2,*

, Jose Luis Serrano⁴

, Andrés Márquez^1,2

, Sergi Gallego^1,2

, Inmaculada Pascual^1,3

and Augusto Beléndez^1,2

¹ Instituto Universitario de Física Aplicada a las Ciencias y las Tecnologías, Universidad de Alicante. Apartado 99, 03080 Alicante, Spain

² Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante, Apartado 99, E03080 Alicante, Spain

³ Departamento de Óptica, Farmacología y Anatomía, Universidad de Alicante, Apartado 99, E03080 Alicante, Spain

⁴ Departamento de Ingeniería Minera, Geológica y Cartográfica, Universidad Politécnica de Cartagena, Área de Química Inorgánica, Regional Campus of International Excellence ‘Campus Mare Nostrum’, 30203 Cartagena, Spain

Polymers 2017, 9(7), 298; https://doi.org/10.3390/polym9070298 - 21 Jul 2017

Cited by 7 | Viewed by 6120

Abstract

Schiff’s bases with specific π-electron system have been synthesized and used as additives in holographic polymer-dispersed liquid crystals. It was observed that these substances modify different parameters such as current intensity, voltage, and diffracted light intensity. In addition, the maximum diffraction efficiency obtained [...] Read more.

Schiff’s bases with specific π-electron system have been synthesized and used as additives in holographic polymer-dispersed liquid crystals. It was observed that these substances modify different parameters such as current intensity, voltage, and diffracted light intensity. In addition, the maximum diffraction efficiency obtained in the reconstruction of the holograms is related to the additive molecule. We propose a relationship between this behavior and the molecular structure of these substances. Full article

(This article belongs to the Special Issue Photo-Responsive Polymers)

▼ Show Figures

Figure 1

14 pages, 2414 KiB

Open AccessArticle

Upconversion Nanophosphor-Involved Molecularly Imprinted Fluorescent Polymers for Sensitive and Specific Recognition of Sterigmatocystin

by Jing-Min Liu^1,2, Feng-Zhen Cao³, Guo-Zhen Fang³ and Shuo Wang^1,2,*

¹ Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology & Business University (BTBU), Beijing 100048, China

² School of Medicine, Nankai University, Tianjin 300071, China

³ Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin University of Science and Technology, Tianjin 300457, China

Polymers 2017, 9(7), 299; https://doi.org/10.3390/polym9070299 - 22 Jul 2017

Cited by 17 | Viewed by 5840

Abstract

Originated from the bottom-up synthetic strategy, molecularly imprinted polymers (MIPs) possess the inherent ability of selective and specific recognition and binding of the target analytes, with their structural cavities that can match the target molecules in respect to size, shape, and functional groups. [...] Read more.

Originated from the bottom-up synthetic strategy, molecularly imprinted polymers (MIPs) possess the inherent ability of selective and specific recognition and binding of the target analytes, with their structural cavities that can match the target molecules in respect to size, shape, and functional groups. Herein, based on the high selectivity of MIPs and the fluorescence properties of the β-NaYF₄:Yb³⁺, Er³⁺ upconversion nanoparticles, MIPs with both specificity and fluorescent signals are fabricated to recognize trace sterigmatocystin (ST) with high selectivity and sensitivity. The structure analogue of ST, 1,8-dihydroxyanthraquinone (DT), was employed as the template molecule, acrylamide as the functional monomer, 3-methacryloyloxypropyltrimethoxysilane as the crosslinking agent, and a new molecular imprinting technique of non-aqueous sol-gel method is used to synthesize a molecularly imprinted material with high selectivity to ST. Under optimal conditions, the fluorescence enhancement of fluorescent MIPs increased as the concentration of ST increased. In the range of 0.05–1.0 mg L⁻¹, fluorescence enhancement and the concentration showed a good linear relationship with a detection limit of 0.013 mg L⁻¹. Real sample analysis achieved the recoveries of 83.8–88.8% (RSD 5.1%) for rice, 82.1–87.5% (RSD 4.6%) for maize, and 80.6–89.2% (RSD 3.0%) for soybeans, respectively, revealing the feasibility of the developed method. Full article

▼ Show Figures

Graphical abstract

18 pages, 5377 KiB

Open AccessArticle

Enhancement of Wound Healing in Normal and Diabetic Mice by Topical Application of Amorphous Polyphosphate. Superior Effect of a Host–Guest Composite Material Composed of Collagen (Host) and Polyphosphate (Guest)

by Werner E.G. Müller^1,*, Dinko Relkovic², Maximilian Ackermann³, Shunfeng Wang¹, Meik Neufurth¹

, Andrea Paravic Radicevic², Hiroshi Ushijima⁴, Heinz-C Schröder¹ and Xiaohong Wang^1,*

¹ ERC Advanced Investigator Grant Research Group at the Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University, Mainz, Duesbergweg 6, 55128 Mainz, Germany

² Fidelta Ltd., Prilaz baruna Filipovića 29, 10000 Zagreb, Croatia

³ Institute of Functional and Clinical Anatomy, University Medical Center of the Johannes Gutenberg University, Johann Joachim Becher Weg 13, D-55099 Mainz, Germany

⁴ Division of Microbiology, Department of Pathology and Microbiology, Nihon University School of Medicine, 30-1 Oyaguchi Kamicho, Itabashi-ku, Tokyo, 173-8610, Japan

Polymers 2017, 9(7), 300; https://doi.org/10.3390/polym9070300 - 22 Jul 2017

Cited by 33 | Viewed by 7494

Abstract

The effect of polyphosphate (polyP) microparticles on wound healing was tested both in vitro and in a mice model in vivo. Two approaches were used: pure salts of polyphosphate, fabricated as amorphous microparticles (MPs, consisting of calcium and magnesium salts of polyP, “Ca–polyp-MPs” [...] Read more.

The effect of polyphosphate (polyP) microparticles on wound healing was tested both in vitro and in a mice model in vivo. Two approaches were used: pure salts of polyphosphate, fabricated as amorphous microparticles (MPs, consisting of calcium and magnesium salts of polyP, “Ca–polyp-MPs” and “Mg–polyp-MPs”), and host–guest composite particles, prepared from amorphous collagen (host) and polyphosphate (guest), termed “col/polyp-MPs”. Animal experiments with polyP on healing of excisional wounds were performed using both normal mice and diabetic mice. After a healing period of 7 days “Ca–polyp-MP” significantly improved re-epithelialization in normal mice from 31% (control) to 72% (polyP microparticle-treated). Importantly, in diabetic mice, particularly the host–guest particles “col/polyp-MP”, increased the rate of re-epithelialization to ≈40% (control, 23%). In addition, those particles increased the expression of COL-I and COL-III as well as the expression the α-smooth muscle actin and the plasminogen activator inhibitor-1. We propose that “Ca–polyp-MPs”, and particularly the host–guest “col/polyp-MPs” are useful for topical treatment of wounds. Full article

(This article belongs to the Special Issue Host-Guest Polymer Complexes)

▼ Show Figures

Graphical abstract

13 pages, 2346 KiB

Open AccessArticle

Synthesis and Phase Transition of Poly(N-isopropylacrylamide)-Based Thermo-Sensitive Cyclic Brush Polymer

by Xiaoyan Tu, Chao Meng, Zhe Liu, Lu Sun, Xianshuo Zhang, Mingkui Zhang, Mingrui Sun, Liwei Ma, Mingzhu Liu^* and Hua Wei^*

State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China

Polymers 2017, 9(7), 301; https://doi.org/10.3390/polym9070301 - 23 Jul 2017

Cited by 31 | Viewed by 7286

Abstract

Polymers with advanced topological architectures are promising materials for wide applications due to their structure-generated unique properties different from that of the linear analogues. The elegant integration of stimuli-responsive polymers with such advanced architectures can create novel materials with virtues from both moieties, [...] Read more.

Polymers with advanced topological architectures are promising materials for wide applications due to their structure-generated unique properties different from that of the linear analogues. The elegant integration of stimuli-responsive polymers with such advanced architectures can create novel materials with virtues from both moieties, are thus a hot subject of research for both fundamental and practical investigations. To fabricate cyclic brush polymer-based intelligent materials for biomedical applications, herein, we designed and synthesized thermo-sensitive cyclic brush polymers with poly(N-isopropylacrylamide) (PNIPAAm) brushes by controlled living radical polymerization using cyclic multimacroinitiator. The thermo-induced phase transition behaviors of the resultant cyclic brush polymers with different compositions were investigated in detail by temperature-dependent optical transmittance measurements, and compared with the properties of bottlebrush and linear counterparts. Interestingly, the cloud point transition temperature (Tcp) of cyclic brush PNIPAAm could be regulated by the chain length of PNIPAAm brush. Although the bottlebrush polymers with the same composition exhibited similarly structurally dependent Tcps behaviors to the cyclic brush polymers, the cyclic brush PNIPAAm did show higher critical aggregation concentration (CAC) and enhanced stability against dilution than the bottlebrush counterpart. The readily tailorable Tcps together with the ability to form highly stable nanoparticles makes thermo-sensitive cyclic brush PNIPAAm a promising candidate for controlled drug delivery. Full article

▼ Show Figures

Graphical abstract

14 pages, 4898 KiB

Open AccessArticle

Two-Photon-Induced Microstereolithography of Chitosan-g-Oligolactides as a Function of Their Stereochemical Composition

by Tatiana S. Demina^1,*

, Kseniia N. Bardakova^2,3

, Nikita V. Minaev²

, Eugenia A. Svidchenko¹, Alexander V. Istomin¹, Galina P. Goncharuk¹, Leonid V. Vladimirov⁴, Andrey V. Grachev⁴, Alexander N. Zelenetskii¹, Peter S. Timashev^2,3

and Tatiana A. Akopova¹

¹ Enikolopov Institute of Synthetic Polymer Materials, Russian Academy of Sciences, 70 Profsoyuznaya str., Moscow 117393, Russia

² Institute of Photonic Technologies, Research center “Crystallography and Photonics”, Russian Academy of Sciences, 2 Pionerskaya str., Troitsk, Moscow 142190, Russia

³ Institute for Regenerative Medicine, Sechenov University, 8-2 Trubetskaya st., Moscow 119991, Russia

⁴ Semenov Institute of Chemical Physics, Russian Academy of Sciences, 4 Kosygina str., Moscow 119334, Russia

Polymers 2017, 9(7), 302; https://doi.org/10.3390/polym9070302 - 24 Jul 2017

Cited by 30 | Viewed by 6610

Abstract

Chitosan-g-oligolactide copolymers with relatively long oligolactide grafted chains of various stereochemical compositions have been synthetized via a solvent-free mechanochemical technique and tailored to fabricate three-dimensional hydrogels using two-photon induced microstereolithography. An effect of the characteristics of chitosan and oligolactide used for [...] Read more.

Chitosan-g-oligolactide copolymers with relatively long oligolactide grafted chains of various stereochemical compositions have been synthetized via a solvent-free mechanochemical technique and tailored to fabricate three-dimensional hydrogels using two-photon induced microstereolithography. An effect of the characteristics of chitosan and oligolactide used for the synthesis on the grafting yield and copolymer’s behavior were evaluated using fractional analysis, FTIR-spectroscopy, dynamic light scattering, and UV-spectrophotometry. The lowest copolymer yield was found for the system based on chitosan with higher molecular weight, while the samples consisting of low-molecular weight chitosan showed higher grafting degrees, which were comparable in both the cases of l,l- or l,d-oligolactide grafting. The copolymer processability in the course of two-photon stereolithography was evaluated as a function of the copolymer’s characteristics and stereolithography conditions. The structure and mechanical properties of the model film samples and fabricated 3D hydrogels were studied using optical and scanning electron microscopy, as well as by using tensile and nanoindenter devices. The application of copolymer with oligo(l,d-lactide) side chains led to higher processability during two-photon stereolithography in terms of the response to the laser beam, reproduction of the digital model, and the mechanical properties of the fabricated hydrogels. Full article

(This article belongs to the Collection Polysaccharides)

▼ Show Figures

Figure 1

Review

Jump to: Research

17 pages, 6234 KiB

Open AccessReview

Sialic Acid-Targeted Biointerface Materials and Bio-Applications

by Yuting Xiong¹, Minmin Li², Qi Lu¹

, Guangyan Qing^1,*

and Taolei Sun^1,3,*

¹ State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070, China

² College of Mechanical Engineering, Jiangxi University of Technology, 115 Ziyang Road, Nanchang 330098, China

³ School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, 122 Luoshi Road, Wuhan 430070, China

Polymers 2017, 9(7), 249; https://doi.org/10.3390/polym9070249 - 27 Jun 2017

Cited by 31 | Viewed by 15262

Abstract

Sialic acids (SAs) are typically found as terminal monosaccharides attached to cell surface glycoconjugates, which play crucial roles in various biological processes, and aberrant sialylation is closely associated with many diseases, particularly cancers. As SAs are overexpressed in tumor-associated glycoproteins, the recognition and [...] Read more.

Sialic acids (SAs) are typically found as terminal monosaccharides attached to cell surface glycoconjugates, which play crucial roles in various biological processes, and aberrant sialylation is closely associated with many diseases, particularly cancers. As SAs are overexpressed in tumor-associated glycoproteins, the recognition and specific binding of SA are crucial for monitoring, analyzing and controlling cancer cells, which would have a considerable impact on diagnostic and therapeutic application. However, both effective and selective recognition of SA on the cancer cell surface remains challenging. In recent years, SA-targeted biointerface materials have attracted great attention in various bio-applications, including cancer detection and imaging, drug delivery for cancer therapy and sialylated glycopeptide separation or enrichment. This review provides an overview of recent advances in SA-targeted biointerface materials and related bio-applications. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Biointerface)

▼ Show Figures

Graphical abstract

15 pages, 3306 KiB

Open AccessReview

Particle Distribution of Solid Flame Retardants in Infusion Moulded Composites

by Ákos Pomázi

and Andrea Toldy^*

Department of Polymer Engineering, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, Műegyetem rkp. 3., H-1111 Budapest, Hungary

Polymers 2017, 9(7), 250; https://doi.org/10.3390/polym9070250 - 28 Jun 2017

Cited by 29 | Viewed by 6410

Abstract

Resin transfer moulding (RTM) is commonly used for the production of high-performance fibre-reinforced polymer composites. In numerous application areas, the addition of fillers is necessary to enhance some properties of the polymer matrix or provide it with additional properties, such as flame retardancy. [...] Read more.

Resin transfer moulding (RTM) is commonly used for the production of high-performance fibre-reinforced polymer composites. In numerous application areas, the addition of fillers is necessary to enhance some properties of the polymer matrix or provide it with additional properties, such as flame retardancy. As many of the applied additives are solid phase, the reinforcement layers may filter the solid phase additive particles during RTM, resulting in a non-uniform distribution and uneven performance. Consequently, the proper distribution of the solid phase additives in composites is of key importance. This review primarily aims at facilitating the production of flame retarded structural composites by RTM in cases where the required fire performance can only be achieved with solid additives. First, the parameters influencing the particle distribution, along with the models describing it, are reviewed. Then, analytical methods for determining the particle distribution in composites manufactured by RTM are presented. Finally, the possible solutions to improve the particle distribution of solid phase additives are outlined. Full article

(This article belongs to the Collection Featured Mini Reviews in Polymer Science)

▼ Show Figures

Graphical abstract

32 pages, 800 KiB

Open AccessReview

Statistical and Dynamical Properties of Topological Polymers with Graphs and Ring Polymers with Knots

by Tetsuo Deguchi^* and Erica Uehara

Department of Physics, Faculty of Core Research, Ochanomizu University, Ohtsuka 2-1-1, Bunkyo-ku, Tokyo 112-8610, Japan

Polymers 2017, 9(7), 252; https://doi.org/10.3390/polym9070252 - 28 Jun 2017

Cited by 28 | Viewed by 8369

Abstract

We review recent theoretical studies on the statistical and dynamical properties of polymers with nontrivial structures in chemical connectivity and those of polymers with a nontrivial topology, such as knotted ring polymers in solution. We call polymers with nontrivial structures in chemical connectivity [...] Read more.

We review recent theoretical studies on the statistical and dynamical properties of polymers with nontrivial structures in chemical connectivity and those of polymers with a nontrivial topology, such as knotted ring polymers in solution. We call polymers with nontrivial structures in chemical connectivity expressed by graphs “topological polymers”. Graphs with no loop have only trivial topology, while graphs with loops such as multiple-rings may have nontrivial topology of spatial graphs as embeddings in three dimensions, e.g., knots or links in some loops. We thus call also such polymers with nontrivial topology “topological polymers”, for simplicity. For various polymers with different structures in chemical connectivity, we numerically evaluate the mean-square radius of gyration and the hydrodynamic radius systematically through simulation. We evaluate the ratio of the gyration radius to the hydrodynamic radius, which we expect to be universal from the viewpoint of the renormalization group. Furthermore, we show that the short-distance intrachain correlation is much enhanced for real topological polymers (the Kremer–Grest model) expressed with complex graphs. We then address topological properties of ring polymers in solution. We define the knotting probability of a knot K by the probability that a given random polygon or self-avoiding polygon of N vertices has the knot K. We show a formula for expressing it as a function of the number of segments N, which gives good fitted curves to the data of the knotting probability versus N. We show numerically that the average size of self-avoiding polygons with a fixed knot can be much larger than that of no topological constraint if the excluded volume is small. We call it “topological swelling”. Full article

(This article belongs to the Special Issue Semiflexible Polymers)

▼ Show Figures

Figure 1

21 pages, 5539 KiB

Open AccessReview

Glucose Oxidase-Based Glucose-Sensitive Drug Delivery for Diabetes Treatment

by Li Zhao¹, Liyan Wang¹, Yuhan Zhang^1,3, Shanshan Xiao¹, Fei Bi¹, Jianyu Zhao^2,*, Guangqing Gai^1,* and Jianxun Ding^4,*

¹ Laboratory of Building Energy-Saving Technology Engineering, College of Material Science and Engineering, Jilin Jianzhu University, Changchun 130118, Jilin, China

² Department of Endocrinology, China-Japan Union Hospital of Jilin University, Changchun 130033, Jilin, China

³ School of Phermaceuticel Science and Technology, Dalian University of Technology, Dalian 116024, Liaoning, China

⁴ Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, Jilin, China

Polymers 2017, 9(7), 255; https://doi.org/10.3390/polym9070255 - 29 Jun 2017

Cited by 84 | Viewed by 15658

Abstract

The glucose-sensitive drug delivery systems based on glucose oxidase (GOD), which exhibit highly promising applications in diabetes therapy, have attracted much more interest in recent years. The self-regulated drug delivery systems regulate drug release by glucose concentration automatically and continuously to control the [...] Read more.

The glucose-sensitive drug delivery systems based on glucose oxidase (GOD), which exhibit highly promising applications in diabetes therapy, have attracted much more interest in recent years. The self-regulated drug delivery systems regulate drug release by glucose concentration automatically and continuously to control the blood glucose level (BGL) in normoglycemic state. This review covers the recent advances at the developments of GOD-based glucose-sensitive drug delivery systems and their in vivo applications for diabetes treatment. The applications of GOD-immobilized platforms, such as self-assembly layer-by-layer (LbL) films and polymer vesicles, cross-linking hydrogels and microgels, hybrid mesoporous silica nanoparticles, and microdevices fabricated with insulin reservoirs have been surveyed. The glucose-sensitive drug delivery systems based on GOD are expected to be a typical candidate for smart platforms for potential applications in diabetes therapy. Full article

(This article belongs to the Special Issue Functionally Responsive Polymeric Materials)

▼ Show Figures

Graphical abstract

19 pages, 6510 KiB

Open AccessReview

Tissue Engineering Bionanocomposites Based on Poly(propylene fumarate)

by Ana M. Diez-Pascual

Analytical Chemistry, Physical Chemistry and Chemical Engineering Department, Faculty of Biology, Environmental Sciences and Chemistry, Alcalá University, 28871 Madrid, Spain

Polymers 2017, 9(7), 260; https://doi.org/10.3390/polym9070260 - 30 Jun 2017

Cited by 48 | Viewed by 11783

Abstract

Poly(propylene fumarate) (PPF) is a linear and unsaturated copolyester based on fumaric acid that has been widely investigated for tissue engineering applications in recent years due to its tailorable mechanical performance, adjustable biodegradability and exceptional biocompatibility. In order to improve its mechanical properties [...] Read more.

Poly(propylene fumarate) (PPF) is a linear and unsaturated copolyester based on fumaric acid that has been widely investigated for tissue engineering applications in recent years due to its tailorable mechanical performance, adjustable biodegradability and exceptional biocompatibility. In order to improve its mechanical properties and spread its range of practical applications, novel approaches need to be developed such as the incorporation of fillers or polymer blending. Thus, PPF-based bionanocomposites reinforced with different amounts of single-walled carbon nanotubes (SWCNT), multi-walled carbon nanotubes (MWCNT), graphene oxide nanoribbons (GONR), graphite oxide nanoplatelets (GONP), polyethylene glycol-functionalized graphene oxide (PEG-GO), polyethylene glycol-grafted boron nitride nanotubes (PEG-g-BNNTs) and hydroxyapatite (HA) nanoparticles were synthesized via sonication and thermal curing, and their morphology, biodegradability, cytotoxicity, thermal, rheological, mechanical and antibacterial properties were investigated. An increase in the level of hydrophilicity, biodegradation rate, stiffness and strength was found upon increasing nanofiller loading. The nanocomposites retained enough rigidity and strength under physiological conditions to provide effective support for bone tissue formation, showed antibacterial activity against Gram-positive and Gram-negative bacteria, and did not induce toxicity on human dermal fibroblasts. These novel biomaterials demonstrate great potential to be used for bone tissue engineering applications. Full article

(This article belongs to the Special Issue Advance of Polymers Applied to Biomedical Applications: Biointerface)

▼ Show Figures

Figure 1

37 pages, 3283 KiB

Open AccessReview

Poly(lactic acid) Composites Containing Carbon-Based Nanomaterials: A Review

by Carolina Gonçalves¹

, Inês C. Gonçalves^2,3, Fernão D. Magalhães¹

and Artur M. Pinto^1,2,3,*

¹ LEPABE—Faculdade de Engenharia, Universidade do Porto, rua Dr. Roberto Frias, Porto 4200-465, Portugal

² INEB—National Institute of Biomedical Engineering, University of Porto, Rua do Campo Alegre, 823, Porto 4150-180, Portugal

³ i3S—Institute for Innovation and Health Research, University of Porto, Rua Alfredo Allen, 208, Porto 4200-135, Portugal

Polymers 2017, 9(7), 269; https://doi.org/10.3390/polym9070269 - 6 Jul 2017

Cited by 144 | Viewed by 13331

Abstract

Poly(lactic acid) (PLA) is a green alternative to petrochemical commodity plastics, used in packaging, agricultural products, disposable materials, textiles, and automotive composites. It is also approved by regulatory authorities for several biomedical applications. However, for some uses it is required that some of [...] Read more.

Poly(lactic acid) (PLA) is a green alternative to petrochemical commodity plastics, used in packaging, agricultural products, disposable materials, textiles, and automotive composites. It is also approved by regulatory authorities for several biomedical applications. However, for some uses it is required that some of its properties be improved, namely in terms of thermo-mechanical and electrical performance. The incorporation of nanofillers is a common approach to attain this goal. The outstanding properties of carbon-based nanomaterials (CBN) have caused a surge in research works dealing with PLA/CBN composites. The available information is compiled and reviewed, focusing on PLA/CNT (carbon nanotubes) and PLA/GBM (graphene-based materials) composites. The production methods, and the effects of CBN loading on PLA properties, namely mechanical, thermal, electrical, and biological, are discussed. Full article

(This article belongs to the Special Issue Graphene-Polymer Composites)

▼ Show Figures

Figure 1

36 pages, 10725 KiB

Open AccessReview

Vesicles from Amphiphilic Dumbbells and Janus Dendrimers: Bioinspired Self-Assembled Structures for Biomedical Applications

by Soraya Taabache^1,2 and Annabelle Bertin^1,3,*

¹ Federal Institute for Materials Research and Testing (BAM), Department 6.0, D-12205 Berlin, Germany

² Fraunhofer ICT-IMM, D-55129 Mainz, Germany

³ Institute of Chemistry and Biochemistry, Freie Universität Berlin, D-14195 Berlin, Germany

Polymers 2017, 9(7), 280; https://doi.org/10.3390/polym9070280 - 12 Jul 2017

Cited by 24 | Viewed by 12075

Abstract

The current review focuses on vesicles obtained from the self-assembly of two types of dendritic macromolecules, namely amphiphilic Janus dendrimers (forming dendrimersomes) and amphiphilic dumbbells. In the first part, we will present some synthetic strategies and the various building blocks that can be [...] Read more.

The current review focuses on vesicles obtained from the self-assembly of two types of dendritic macromolecules, namely amphiphilic Janus dendrimers (forming dendrimersomes) and amphiphilic dumbbells. In the first part, we will present some synthetic strategies and the various building blocks that can be used to obtain dendritic-based macromolecules, thereby showing their structural versatility. We put our focus on amphiphilic Janus dendrimers and amphiphilic dumbbells that form vesicles in water but we also encompass vesicles formed thereof in organic solvents. The second part of this review deals with the production methods of these vesicles at the nanoscale but also at the microscale. Furthermore, the influence of various parameters (intrinsic to the amphiphilic JD and extrinsic—from the environment) on the type of vesicle formed will be discussed. In the third part, we will review the numerous biomedical applications of these vesicles of nano- or micron-size. Full article

(This article belongs to the Special Issue Bio-inspired and Bio-based Polymers)

▼ Show Figures

Graphical abstract

Journal Menu

Journal Browser

Polymers, Volume 9, Issue 7 (July 2017) – 62 articles

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI