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Polymers, Volume 14, Issue 20 (October-2 2022) – 217 articles

Cover Story (view full-size image): The availability of growing amounts of waste biomasses suggests their potential use to produce biocomposites as a replacement for wood-like materials. This requires the biomass to be characterized as such and when coupled with a polymer. In this work, four different biomasses, namely holm oak, licorice root, palm leaf, and willow, are introduced in amounts up to 30 wt.% in a compatibilized polypropylene matrix and characterized from a chemical, thermal, and mechanical point of view. This is aimed at offering information on how the introduction of biomasses modifies the thermal degradation and the viscoelastic behavior of the polymer. View this paper
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12 pages, 4835 KiB  
Article
Synthesis of Functional Polyesters N-(2,3-epoxypropyl)-4,5,6,7-tetrahydroindole by Anionic Ring-Opening Polymerization
by Marina Markova, Artem Emel’yanov, Inna Tatarinova and Alexander Pozdnyakov
Polymers 2022, 14(20), 4467; https://doi.org/10.3390/polym14204467 - 21 Oct 2022
Cited by 1 | Viewed by 1172
Abstract
The functional polyethers of N-(2,3-epoxypropyl)-4,5,6,7-tetrahydroindole (in up to 61% yield, Mw = 8.7–11.7 kDa) and copolymers with ethylene glycol methylglycidyl ether (Mw = 5.6–14.2 kDa) and ethylene glycol vinylglycidyl ether (Mw = 6.4–12.3 kDa) have been synthesized via anionic [...] Read more.
The functional polyethers of N-(2,3-epoxypropyl)-4,5,6,7-tetrahydroindole (in up to 61% yield, Mw = 8.7–11.7 kDa) and copolymers with ethylene glycol methylglycidyl ether (Mw = 5.6–14.2 kDa) and ethylene glycol vinylglycidyl ether (Mw = 6.4–12.3 kDa) have been synthesized via anionic ring-opening polymerization in the presence of KOH without solvent. The polymerization involves the opening of the epoxy ring to deliver the linear polyethers bearing free tetrahydroindole rings and oxyethylene or vinyloxy groups in the side chain. The polyethers are soluble in ethanol, benzene, chloroform, dioxane, DMF, and DMSO. The polyethers obtained exhibit the properties of high-resistance organic semiconductors: their electrical conductivity reaches 10−14 S/cm. Full article
(This article belongs to the Special Issue Properties and Characterization of Polymers in Nanomaterials)
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11 pages, 2462 KiB  
Article
Improving the Performance of Polymer Solar Cells with Benzo[ghi]perylenetriimide-Based Small-Molecules as Interfacial Layers
by Yang-Yen Yu, Hung-Cheng Chen, Kai-Yu Shih, Yan-Cheng Peng, Bing-Huang Jiang, Chao-I Liu, Ming-Wei Hsu, Chi-Ching Kuo and Chih-Ping Chen
Polymers 2022, 14(20), 4466; https://doi.org/10.3390/polym14204466 - 21 Oct 2022
Viewed by 1418
Abstract
In this study, we prepared three benzo[ghi]perylenetriimide (BPTI) conjugated molecules as electron-transporting surface-modifying layers for polymer solar cells (PSCs). These three BPTI derivatives differed in the nature of their terminal functionalities, featuring butylamine (C3NH2), propylammonium iodide (C [...] Read more.
In this study, we prepared three benzo[ghi]perylenetriimide (BPTI) conjugated molecules as electron-transporting surface-modifying layers for polymer solar cells (PSCs). These three BPTI derivatives differed in the nature of their terminal functionalities, featuring butylamine (C3NH2), propylammonium iodide (C3NH3I), and butyldimethylamine (C3DMA) units, respectively. We evaluated the optoelectronic properties of PTB7-Th: PC71BM blends modified with these interfacial layers, as well as the performance of resulting PSCs. We used UV–Vis spectroscopy, atomic force microscopy, surface energy analysis, ultraviolet photoelectron spectroscopy, and photoelectric flow measurements to examine the phenomena behind the changes in the optoelectronic behavior of these blend films. The presence of a BPTI derivative changed the energy band alignment at the ZnO–active layer interface, leading to the ZnO film behaving more efficiently as an electron-extraction electrode. Modifying the ZnO surface with the BPTI-C3NH3I derivative resulted in a best power conversion efficiency (PCE) of 10.2 ± 0.53% for the PTB7-Th:PC71BM PSC (cf. PCE of the control device of 9.1 ± 0.13%). In addition, modification of a PM6:Y6:PCBM PSC with the BPTI-C3NH3I derivative increased its PCE from 15.6 ± 0.25% to 16.5 ± 0.18%. Thus, BPTI derivatives appear to have potential as IFLs when developing high-performance PSCs, and might also be applicable in other optoelectronic devices. Full article
(This article belongs to the Special Issue Applications of Polymers in Energy and Environmental Sciences II)
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11 pages, 1330 KiB  
Article
Fire Resistance Evaluation of New Wooden Composites Containing Waste Rubber from Automobiles
by Vladimír Mancel, Iveta Čabalová, Jozef Krilek, Roman Réh, Martin Zachar and Tereza Jurczyková
Polymers 2022, 14(20), 4465; https://doi.org/10.3390/polym14204465 - 21 Oct 2022
Cited by 6 | Viewed by 1556
Abstract
Particleboards containing waste rubber (tires and mixtures of isolators and carpets) filler were evaluated from the point of view of its flammability. The assessment of the utilization of these composites in the construction industry was analyzed through the determination of their spontaneous ignition [...] Read more.
Particleboards containing waste rubber (tires and mixtures of isolators and carpets) filler were evaluated from the point of view of its flammability. The assessment of the utilization of these composites in the construction industry was analyzed through the determination of their spontaneous ignition temperatures, mass burning rate and calorific value. Based on the results of spontaneous ignition temperatures, similar values between particleboards and particleboards containing 10%, 15% and 20% of waste tires were obtained. The average time was from 298 s to 309 s and the average temperature was from 428.1 °C to 431.7 °C. For the mass burning rate, there were similar results between particleboards and particleboards containing 10% of waste tires and waste rubber. The time to initiation was 34 s and the time to reaching a maximal burning rate was from 66 s to 68 s. The calorimetry results showed similar properties for the calorimetric value and ash content in particleboards and particleboards containing 10% of waste tires and waste rubber. The calorific value was from 18.4 MJ·kg−1 to 19.7 MJ·kg−1 and the ash content from 0.5% to 2.9%. Full article
(This article belongs to the Special Issue Wood Waste-Based Composites)
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12 pages, 3382 KiB  
Article
Failure Prediction in 3D Printed Kevlar/Glass Fiber-Reinforced Nylon Structures with a Hole and Different Fiber Orientations
by Mohammed Aqeel Albadrani
Polymers 2022, 14(20), 4464; https://doi.org/10.3390/polym14204464 - 21 Oct 2022
Cited by 6 | Viewed by 1751
Abstract
This study examined the mechanical performance of 3D-printed, fiber-reinforced composites with a rectangular shape and a hole at one end. Nyon-6 was selected as a polymer matrix, and glass or Kevlar fibers were selected as continuous fibers due to their wide range of [...] Read more.
This study examined the mechanical performance of 3D-printed, fiber-reinforced composites with a rectangular shape and a hole at one end. Nyon-6 was selected as a polymer matrix, and glass or Kevlar fibers were selected as continuous fibers due to their wide range of applications. Nylon is an engineering thermoplastic; reinforcing it with fibers, such as glass fiber or Kevlar, can significantly improve its mechanical properties. An analytical model was constructed based on the volume average stiffness approach to predict the mechanical properties of 3D-printed specimens. A numerical model was built to predict failure modes and damage in 3D-printed specimens with different fiber orientations. The stress–strain relationship was linear in all composites. For Kevlar-based composites, the maximum stress was 1.7 MPa, 3.62 MPa, 2.2 MPa, 1.0 MPa, and 1.4 MPa for the orientation angles of 0°, 22.5°, 45°, 67.5°, and 90°, respectively. Overall, Kevlar-based composites exhibited mechanical properties superior to those of glass-based composites. The effect of the fiber orientation was also different between the two systems. The simulation results predicted that the failure propagation begins in the areas close to the hole. Notably, the level of agreement between the simulated and experimental results varied depending on the fiber type and orientation, reflecting the complex interplay between multiple fibers, matrix interactions, and stress transfer. Full article
(This article belongs to the Section Polymer Composites and Nanocomposites)
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20 pages, 4626 KiB  
Article
Physical Properties of Fast-Growing Wood-Polymer Nano Composite Synthesized through TiO2 Nanoparticle Impregnation
by Istie Rahayu, Wayan Darmawan, Deded Sarip Nawawi, Esti Prihatini, Rohmat Ismail and Gilang Dwi Laksono
Polymers 2022, 14(20), 4463; https://doi.org/10.3390/polym14204463 - 21 Oct 2022
Cited by 7 | Viewed by 2064
Abstract
Mangium (Acacia mangium Willd.) is a fast-growing wood that is widely grown in Indonesia. The impregnation method is needed to improve the qualities of the wood. In this study, TiO2 nanoparticle (79.17 nm) was produced using the hydrothermal method. The purpose [...] Read more.
Mangium (Acacia mangium Willd.) is a fast-growing wood that is widely grown in Indonesia. The impregnation method is needed to improve the qualities of the wood. In this study, TiO2 nanoparticle (79.17 nm) was produced using the hydrothermal method. The purpose of this study was to analyze the effect of TiO2 nanoparticle impregnation on the density and dimensional stability of mangium and the effectiveness of the presence of TiO2 nanoparticle in wood in degrading pollutants. The mangium samples (2 cm × 2 cm × 2 cm) were placed inside impregnation tube. The impregnation solutions included water (untreated), 1% TiO2 nanoparticle, and 5% TiO2 nanoparticles. The samples were analyzed for density, weight percent gain (WPG) dan bulking effect (BE). Samples were also analyzed by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). TiO2 nanoparticle resulted in an increase in density, WPG, and BE-treated mangium. Based on XRD and FTIR results, TiO2 nanoparticle was successfully impregnated into mangium wood. Scanning electron microscopy–energy-dispersive X-ray spectroscopy analysis indicated that TiO2 nanoparticle covered the surface of the wood cells. The TiO2-impregnated mangium wood has a higher photocatalyst activity than untreated, indicating better protection from UV radiation and pollutants. Full article
(This article belongs to the Special Issue Advances in Wood Based Composites)
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14 pages, 3656 KiB  
Article
Low Dielectric Properties and Transmission Loss of Polyimide/Organically Modified Hollow Silica Nanofiber Composites
by Shu-Yang Lin, Yu-Min Ye, Erh-Ching Chen and Tzong-Ming Wu
Polymers 2022, 14(20), 4462; https://doi.org/10.3390/polym14204462 - 21 Oct 2022
Cited by 5 | Viewed by 2447
Abstract
In this study, a series of low dielectric constant and transmission loss of polyimide (PI)/organically modified hollow silica nanofiber (m-HSNF) nanocomposites were synthesized via two-step polymerization. Two different PIs were fabricated using two types of diamine monomers with or without fluorine-containing groups and [...] Read more.
In this study, a series of low dielectric constant and transmission loss of polyimide (PI)/organically modified hollow silica nanofiber (m-HSNF) nanocomposites were synthesized via two-step polymerization. Two different PIs were fabricated using two types of diamine monomers with or without fluorine-containing groups and biphenylene structure of dianhydride. The chemical structure and morphology of the fabricated composites were characterized using Nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) and field-emission scanning electron microscopy (FESEM). The two-step polymerization process successfully manufactured and converted from polyamic acid to polyimide after thermal imidization was proved by the NMR and FTIR results. The FESEM and their related energy-dispersive X-ray spectroscopy (EDS) images of nanocomposites indicate that the m-HSNF is extremely dispersed into the polyimide matrix. The high-frequency dielectric constants of the nanocomposite materials decrease as the presence of fluorine-containing groups in diamine monomers and the loadings of the m-HSNF increase. These findings are probably attributed to the presence of the steric hindrance effect brought by trifluoromethyl groups, and the m-HSNF can disrupt the chain packing and increase the free volume, thus reducing the dielectric properties of polyimides. The transmission loss and its related uncertainty of fabricated composite materials contain excellent performance, suggesting that the fabricated materials could be used as substrate materials for 5G printed circuit board. Full article
(This article belongs to the Special Issue Smart and Functional Polymer Composites)
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30 pages, 8195 KiB  
Review
The Frontiers of Functionalized Nanocellulose-Based Composites and Their Application as Chemical Sensors
by Mohd Nor Faiz Norrrahim, Victor Feizal Knight, Norizan Mohd Nurazzi, Mohd Azwan Jenol, Muhammad Syukri Mohamad Misenan, Nurjahirah Janudin, Noor Azilah Mohd Kasim, Muhammad Faizan A. Shukor, Rushdan Ahmad Ilyas, Muhammad Rizal Muhammad Asyraf and Jesuarockiam Naveen
Polymers 2022, 14(20), 4461; https://doi.org/10.3390/polym14204461 - 21 Oct 2022
Cited by 22 | Viewed by 2405
Abstract
Chemical sensors are a rapidly developing technology that has received much attention in diverse industries such as military, medicine, environmental surveillance, automotive power and mobility, food manufacturing, infrastructure construction, product packaging and many more. The mass production of low-cost devices and components for [...] Read more.
Chemical sensors are a rapidly developing technology that has received much attention in diverse industries such as military, medicine, environmental surveillance, automotive power and mobility, food manufacturing, infrastructure construction, product packaging and many more. The mass production of low-cost devices and components for use as chemical sensors is a major driving force for improvements in each of these industries. Recently, studies have found that using renewable and eco-friendly materials would be advantageous for both manufacturers and consumers. Thus, nanotechnology has led to the investigation of nanocellulose, an emerging and desirable bio-material for use as a chemical sensor. The inherent properties of nanocellulose, its high tensile strength, large specific surface area and good porous structure have many advantages in its use as a composite material for chemical sensors, intended to decrease response time by minimizing barriers to mass transport between an analyte and the immobilized indicator in the sensor. Besides which, the piezoelectric effect from aligned fibers in nanocellulose composites is beneficial for application in chemical sensors. Therefore, this review presents a discussion on recent progress and achievements made in the area of nanocellulose composites for chemical sensing applications. Important aspects regarding the preparation of nanocellulose composites using different functionalization with other compounds are also critically discussed in this review. Full article
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24 pages, 3929 KiB  
Article
In Vitro and In Vivo Cell-Interactions with Electrospun Poly (Lactic-Co-Glycolic Acid) (PLGA): Morphological and Immune Response Analysis
by Ana Chor, Christina Maeda Takiya, Marcos Lopes Dias, Raquel Pires Gonçalves, Tatiana Petithory, Jefferson Cypriano, Leonardo Rodrigues de Andrade, Marcos Farina and Karine Anselme
Polymers 2022, 14(20), 4460; https://doi.org/10.3390/polym14204460 - 21 Oct 2022
Cited by 5 | Viewed by 1907
Abstract
Random electrospun three-dimensional fiber membranes mimic the extracellular matrix and the interfibrillar spaces promotes the flow of nutrients for cells. Electrospun PLGA membranes were analyzed in vitro and in vivo after being sterilized with gamma radiation and bioactivated with fibronectin or collagen. Madin-Darby [...] Read more.
Random electrospun three-dimensional fiber membranes mimic the extracellular matrix and the interfibrillar spaces promotes the flow of nutrients for cells. Electrospun PLGA membranes were analyzed in vitro and in vivo after being sterilized with gamma radiation and bioactivated with fibronectin or collagen. Madin-Darby Canine Kidney (MDCK) epithelial cells and primary fibroblast-like cells from hamster’s cheek paunch proliferated over time on these membranes, evidencing their good biocompatibility. Cell-free irradiated PLGA membranes implanted on the back of hamsters resulted in a chronic granulomatous inflammatory response, observed after 7, 15, 30 and 90 days. Morphological analysis of implanted PLGA using light microscopy revealed epithelioid cells, Langhans type of multinucleate giant cells (LCs) and multinucleated giant cells (MNGCs) with internalized biomaterial. Lymphocytes increased along time due to undegraded polymer fragments, inducing the accumulation of cells of the phagocytic lineage, and decreased after 90 days post implantation. Myeloperoxidase+ cells increased after 15 days and decreased after 90 days. LCs, MNGCs and capillaries decreased after 90 days. Analysis of implanted PLGA after 7, 15, 30 and 90 days using transmission electron microscope (TEM) showed cells exhibiting internalized PLGA fragments and filopodia surrounding PLGA fragments. Over time, TEM analysis showed less PLGA fragments surrounded by cells without fibrous tissue formation. Accordingly, MNGC constituted a granulomatous reaction around the polymer, which resolves with time, probably preventing a fibrous capsule formation. Finally, this study confirms the biocompatibility of electrospun PLGA membranes and their potential to accelerate the healing process of oral ulcerations in hamsters’ model in association with autologous cells. Full article
(This article belongs to the Special Issue Biomaterials for Tissue Engineering and Regeneration)
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18 pages, 3167 KiB  
Article
In Vitro and In Vivo Biocompatible and Controlled Resveratrol Release Performances of HEMA/Alginate and HEMA/Gelatin IPN Hydrogel Scaffolds
by Jovana S. Vuković, Vuk V. Filipović, Marija M. Babić Radić, Marija Vukomanović, Dusan Milivojevic, Tatjana Ilic-Tomic, Jasmina Nikodinovic-Runic and Simonida Lj. Tomić
Polymers 2022, 14(20), 4459; https://doi.org/10.3390/polym14204459 - 21 Oct 2022
Cited by 7 | Viewed by 2019
Abstract
Scaffold hydrogel biomaterials designed to have advantageous biofunctional properties, which can be applied for controlled bioactive agent release, represent an important concept in biomedical tissue engineering. Our goal was to create scaffolding materials that mimic living tissue for biomedical utilization. In this study, [...] Read more.
Scaffold hydrogel biomaterials designed to have advantageous biofunctional properties, which can be applied for controlled bioactive agent release, represent an important concept in biomedical tissue engineering. Our goal was to create scaffolding materials that mimic living tissue for biomedical utilization. In this study, two novel series of interpenetrating hydrogel networks (IPNs) based on 2-hydroxyethyl methacrylate/gelatin and 2-hydroxyethyl methacrylate/alginate were crosslinked using N-ethyl-N′-(3-dimethyl aminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). Characterization included examining the effects of crosslinker type and concentration on structure, morphological and mechanical properties, in vitro swelling, hydrophilicity as well as on the in vitro cell viability (fibroblast cells) and in vivo (Caenorhabditis elegans) interactions of novel biomaterials. The engineered IPN hydrogel scaffolds show an interconnected pore morphology and porosity range of 62.36 to 85.20%, favorable in vitro swelling capacity, full hydrophilicity, and Young’s modulus values in the range of 1.40 to 7.50 MPa. In vitro assay on healthy human fibroblast (MRC5 cells) by MTT test and in vivo (Caenorhabditis elegans) survival assays show the advantageous biocompatible properties of novel IPN hydrogel scaffolds. Furthermore, in vitro controlled release study of the therapeutic agent resveratrol showed that these novel scaffolding systems are suitable controlled release platforms. The results revealed that the use of EDC and the combination of EDC/NHS crosslinkers can be applied to prepare and tune the properties of the IPN 2-hydroxyethyl methacrylate/alginate and 2-hydroxyethyl methacrylate/gelatin hydrogel scaffolds series, which have shown great potential for biomedical engineering applications. Full article
(This article belongs to the Special Issue Polymer Scaffolds for Tissue Engineering)
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17 pages, 6915 KiB  
Article
Copper Nanoparticles Decorated Alginate/Cobalt-Doped Cerium Oxide Composite Beads for Catalytic Reduction and Photodegradation of Organic Dyes
by Hamed A. Alshaikhi, Abdullah M. Asiri, Khalid A. Alamry, Hadi M. Marwani, Soliman Y. Alfifi and Sher Bahadar Khan
Polymers 2022, 14(20), 4458; https://doi.org/10.3390/polym14204458 - 21 Oct 2022
Cited by 10 | Viewed by 1615
Abstract
Cobalt-doped cerium oxide (Co–CeO2) was synthesized and wrapped inside alginate (Alg) hydrogel beads (Alg/Co–CeO2). Further, copper nanoparticles (Cu) were grown on Alg/Co–CeO2 beads. Cu decorated Alg/Co–CeO2 composite beads (Cu@Alg/Co–CeO2) were tested as a catalyst for [...] Read more.
Cobalt-doped cerium oxide (Co–CeO2) was synthesized and wrapped inside alginate (Alg) hydrogel beads (Alg/Co–CeO2). Further, copper nanoparticles (Cu) were grown on Alg/Co–CeO2 beads. Cu decorated Alg/Co–CeO2 composite beads (Cu@Alg/Co–CeO2) were tested as a catalyst for the solar-assisted photodegradation and NaBH4-assisted reduction of organic pollutants. Among different dyes, Cu@Alg/Co–CeO2 was found to be the best catalyst for the photodegradation of acridine orange (ArO) under solar light and efficient in reducing methyl orange (MO) with the aid of NaBH4. Cu@Alg/Co–CeO2 decolorized ArO up to 75% in 5 h under solar light, while 97% of MO was reduced in 11 min. The decolorization efficiency of Cu@Alg/Co–CeO2 was further optimized by varying different parameters. Thus, the designed catalyst provides a promising way for efficient oxidation and reduction of pollutants from industrial effluents. Full article
(This article belongs to the Special Issue Smart Nanocomposites for Multiple Applications)
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16 pages, 2929 KiB  
Review
Thia-Michael Reaction: The Route to Promising Covalent Adaptable Networks
by Dimitri Berne, Vincent Ladmiral, Eric Leclerc and Sylvain Caillol
Polymers 2022, 14(20), 4457; https://doi.org/10.3390/polym14204457 - 21 Oct 2022
Cited by 13 | Viewed by 3595
Abstract
While the Michael addition has been employed for more than 130 years for the synthesis of a vast diversity of compounds, the reversibility of this reaction when heteronucleophiles are involved has been generally less considered. First applied to medicinal chemistry, the reversible character [...] Read more.
While the Michael addition has been employed for more than 130 years for the synthesis of a vast diversity of compounds, the reversibility of this reaction when heteronucleophiles are involved has been generally less considered. First applied to medicinal chemistry, the reversible character of the hetero-Michael reactions has recently been explored for the synthesis of Covalent Adaptable Networks (CANs), in particular the thia-Michael reaction and more recently the aza-Michael reaction. In these cross-linked networks, exchange reactions take place between two Michael adducts by successive dissociation and association steps. In order to understand and precisely control the exchange in these CANs, it is necessary to get an insight into the critical parameters influencing the Michael addition and the dissociation rates of Michael adducts by reconsidering previous studies on these matters. This review presents the progress in the understanding of the thia-Michael reaction over the years as well as the latest developments and plausible future directions to prepare CANs based on this reaction. The potential of aza-Michael reaction for CANs application is highlighted in a specific section with comparison with thia-Michael-based CANs. Full article
(This article belongs to the Section Polymer Chemistry)
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12 pages, 4824 KiB  
Article
The Physicochemical Characterization of New “Green” Epoxy-Resin Hardener Made from PET Waste
by Grigorii K. Sterligov, Sergey A. Rzhevskiy, Dilshodakhon K. Isaeva, Nikita M. Belov, Maria A. Rasskazova, Egor A. Drokin, Maxim A. Topchiy, Lidiya I. Minaeva, Alexander V. Babkin, Erdni M. Erdni-Goryaev, Alexey V. Kepman and Andrey F. Asachenko
Polymers 2022, 14(20), 4456; https://doi.org/10.3390/polym14204456 - 21 Oct 2022
Cited by 3 | Viewed by 1612
Abstract
“Green” thermally stable hardener was synthesized from a PET waste. The rigid molecular linear structure of the new hardener suggests that it will provide the polymer matrix with the necessary physical and mechanical characteristics. It also allows the expectation that cured matrix based [...] Read more.
“Green” thermally stable hardener was synthesized from a PET waste. The rigid molecular linear structure of the new hardener suggests that it will provide the polymer matrix with the necessary physical and mechanical characteristics. It also allows the expectation that cured matrix based on this hardener can provide increased toughness. New hardener was used as a curing agent for three epoxy resins—tetraglycidyl methylenedianiline (TGDMA, 111–117 EEW), diglycidylether of bisphenol A (DGEBA, 170-192 EEW) and solid epoxy resin (SER)—with a medium molecular weight (860–930 EEW) based on DGEBA. The mixtures were found to have the highest Tg for the DGEBA resin, and high of that for TGDMA and SER. According to the DMA analysis for two cured matrices, the hardener proved to be no worse than the standard ones, and made it possible to obtain cured matrices with excellent mechanical properties, which allows us to hope for further application of new hardener cured epoxy matrices in appropriate composite materials at high temperatures. Full article
(This article belongs to the Section Polymer Applications)
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12 pages, 3779 KiB  
Article
Preparation and Adsorption Properties of Graphene-Modified, Pitch-Based Carbon Foam Composites
by Hao Li, Tiehu Li, Weibin Deng and Siyuan Kong
Polymers 2022, 14(20), 4455; https://doi.org/10.3390/polym14204455 - 21 Oct 2022
Cited by 9 | Viewed by 1854
Abstract
In view of the good adsorption properties of graphene and carbon foam, they were combined to achieve the optimal matching of microstructures. Taking mesophase pitch as a raw material, pitch-based carbon foam was prepared by the self-foaming method. Graphene gel was prepared as [...] Read more.
In view of the good adsorption properties of graphene and carbon foam, they were combined to achieve the optimal matching of microstructures. Taking mesophase pitch as a raw material, pitch-based carbon foam was prepared by the self-foaming method. Graphene gel was prepared as the second phase to composite with the carbon foam matrix; graphene-modified, pitch-based carbon foam composites were finally obtained. Graphene gel was dispersed in the rich pore structure of carbon foam to improve its agglomeration and the porosity, and the active sites of the composite were further increased; the adsorption properties and mechanical properties of the composites were also significantly improved. The microstructure and morphology of the composites were studied by SEM, XRD and Raman spectroscopy; the compressive property and porosity were also tested. Methylene blue (MB) solution was used to simulate a dye solution for the adsorption test, and the influence of the composite properties and MB solution on the adsorption property was studied. Results showed that the compressive strength of the composite was 13.5 MPa, increased by 53.41%, and the porosity was 58.14%, increased by 24.15%, when compared to raw carbon foam. When the mass of the adsorbent was 150 mg, the initial concentration of the MB solution was 5 mg/L, and the pH value of the MB solution was 11; the graphene-modified carbon foam composites showed the best adsorption effect, with an adsorption rate of 96.3% and an adsorption capacity of 144.45 mg/g. Compared with the raw carbon foam, the adsorption rate and adsorption capacity of the composites were increased by 158.18% and 93.50%, respectively. Full article
(This article belongs to the Special Issue Advances in Recycling of Polymers)
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36 pages, 6456 KiB  
Review
A Review of Development and Utilization for Edible Fungal Polysaccharides: Extraction, Chemical Characteristics, and Bioactivities
by Yujun Sun, Huaqi He, Qian Wang, Xiaoyan Yang, Shengjuan Jiang and Daobing Wang
Polymers 2022, 14(20), 4454; https://doi.org/10.3390/polym14204454 - 21 Oct 2022
Cited by 11 | Viewed by 3081
Abstract
Edible fungi, commonly known as mushrooms, are precious medicinal and edible homologous gifts from nature to us. Because of their distinctive flavor and exceptional nutritional and medicinal value, they have been a frequent visitor to people’s dining tables and have become a hot [...] Read more.
Edible fungi, commonly known as mushrooms, are precious medicinal and edible homologous gifts from nature to us. Because of their distinctive flavor and exceptional nutritional and medicinal value, they have been a frequent visitor to people’s dining tables and have become a hot star in the healthcare, pharmaceutical, and cosmetics industries. Edible fungal polysaccharides (EFPs) are an essential nutrient for edible fungi to exert bioactivity. They have attracted much attention because of their antioxidant, immunomodulatory, antitumor, hypoglycemic, and hypolipidemic bioactivities. As a result, EFPs have demonstrated outstanding potential over the past few decades in various disciplines, including molecular biology, immunology, biotechnology, and pharmaceutical chemistry. However, the complexity of EFPs and the significant impact of mushroom variety and extraction techniques on their bioactivities prevents a complete investigation of their biological features. Therefore, the authors of this paper thoroughly reviewed the comparison of different extraction methods of EFPs and their advantages and disadvantages. In addition, the molecular weight, monosaccharide composition, and glycosidic bond type and backbone structure of EFPs are described in detail. Moreover, the in vitro and in vivo bioactivities of EFPs extracted by different methods and their potential regulatory mechanisms are summarized. These provide a valuable reference for improving the extraction process of EFPs and their production and development in the pharmaceutical field. Full article
(This article belongs to the Special Issue Biodegradable and Natural Polymers)
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14 pages, 3420 KiB  
Article
Synergistic Effects of Diatoms on Intumescent Flame Retardant High Impact Polystyrene System
by Fuhua Lin, Mi Zhang, Xiangyang Li, Shuangdan Mao and Yinghui Wei
Polymers 2022, 14(20), 4453; https://doi.org/10.3390/polym14204453 - 21 Oct 2022
Cited by 1 | Viewed by 1243
Abstract
In this work, aiming to improve the flame retardancy performance of high impact polystyrene (HIPS), HIPS compounds were synthesized with the addition of intumescent flame retardant (IFR: mass ratio of APP and PER was 3:1) and diatoms into HIPS matrix by melt blending [...] Read more.
In this work, aiming to improve the flame retardancy performance of high impact polystyrene (HIPS), HIPS compounds were synthesized with the addition of intumescent flame retardant (IFR: mass ratio of APP and PER was 3:1) and diatoms into HIPS matrix by melt blending method. It was found the IFR/diatoms system exhibited high flame retardant efficiency and catalytic carbonization effect to HIPS matrix in the burning process. The LOI value of HIPS-2 compound with the addition of 28 wt% IFR and 2 wt% diatoms was increased to 29.0% and passed V-0 rating. The value of PHRR for HIPS-2 compound is about 460.58 kW/m2 compared with 937.22 kW/m2 of pure HIPS and the value of THR for HIPS-2 compound is about 32.9 MJ/m2 compared with 62.7 MJ/m2 of pure HIPS, suggesting that the addition of IFR/diatoms system can decrease the values of PHRR and THR, which shows the synergistic effect between IFR and diatoms on reducing heat release. The 21.9% reduction in Av-EHC and 41.4% reduction in TSP seen on introducing an IFR/diatoms system indicates effective smoke suppression, which potentially would significantly reduce the death rate in real fire accidents. The TG-IR results indicated that the IFR/diatoms flame retardant system functioned in the gas phase to suppress the flame. The SEM images showed the char residue produced was more compact and continuous, which suggests that the IFR/diatoms flame retardant system exhibits barrier and catalytic effects to block heat transferring and promote char forming. The tensile strength and impact strength of HIPS-2 compound were 22.95 MPa and 2.63 KJ/m2, respectively. The tensile strength and impact strength were increased by 34.13% and 19.55% compared with that of pure HIPS. Full article
(This article belongs to the Special Issue Recent Development of Polymer Additives)
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11 pages, 2833 KiB  
Article
The In-Situ Mechanical Properties of Carbon Fiber/Epoxy Composite under the Electric-Current Loading
by Runtian Zhu, Xiaolu Li, Cankun Wu, Longji Du and Xusheng Du
Polymers 2022, 14(20), 4452; https://doi.org/10.3390/polym14204452 - 21 Oct 2022
Cited by 3 | Viewed by 1334
Abstract
The Joule heating behavior of the carbon fiber/epoxy composite (CF/EP) was studied in this work, as well as their influence on the in-situ mechanical properties of the composites and their de-icing performance. The equilibrium temperature of the CF/EP composite could be conveniently adjusted [...] Read more.
The Joule heating behavior of the carbon fiber/epoxy composite (CF/EP) was studied in this work, as well as their influence on the in-situ mechanical properties of the composites and their de-icing performance. The equilibrium temperature of the CF/EP composite could be conveniently adjusted by tuning the current according to the Joule’s law. Dynamic mechanical analysis (DMA) tests indicated that the rigidity and stiffness of the fiber-reinforced composite decreased with increasing temperature, and the glass transition temperature (Tg) of the composites was around 104 °C. It was found that the flexural properties of the composites in situ, measured under the electric-current loading, depended on the current value in the range of room temperature to Tg. With increasing the loading current, either the flexural modulus or strength of CF/EP decreased gradually. Such results could be explained that the higher current loading, the larger Joule heat, led to the higher operating temperature of the composite samples and the evolution of their mechanical properties accordingly. Vickers hardness tests indicated that the micro-hardness of the composite decreased with the increase of the operating temperature, which coincided with the evolution of its flexural properties with the electric-current loading. The dependence of the failure behaviors of the CF/EP on the loading current was revealed by the analysis of their fractured surface, where micro-buckling, kinking, fiber pull-out and breakage were involved. A preliminary study indicated that less energy was consumed for the deicing of the same amount of the ice with the CF/EP composite in the case of less electric-current loading. The research on the Joule heating effect of CF/EP and their corresponding mechanical properties benefits the design and direct application of the composites under the electric-current loading. Full article
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14 pages, 9438 KiB  
Article
Quaternary Ammonium-Tethered Phenylboronic Acids Appended Supramolecular Nanomicelles as a Promising Bacteria Targeting Carrier for Nitric Oxide Delivery
by Yu Fang, Haiyan Cui, Xiaoqin Liang, Jianping Yu, Jianrong Wang and Guanghui Zhao
Polymers 2022, 14(20), 4451; https://doi.org/10.3390/polym14204451 - 21 Oct 2022
Cited by 2 | Viewed by 1411
Abstract
The delivery of drugs to focal sites is a central goal and a key challenge in the development of nanomedicine carriers. This strategy can improve the selectivity and bioavailability of the drug while reducing its toxicity. To ensure the specific release of nitric [...] Read more.
The delivery of drugs to focal sites is a central goal and a key challenge in the development of nanomedicine carriers. This strategy can improve the selectivity and bioavailability of the drug while reducing its toxicity. To ensure the specific release of nitric oxide at the site of a bacterial infection without damaging the surrounding normal tissue, we designed a host-guest molecule containing a host molecule with a target moiety and a nitric oxide donor to release nitric oxide. The boronic acid group in the structure of this nanoparticle interacts strongly and specifically with the surface of E. coli. In addition, the quaternary amine salt can interact electrostatically with bacteria, indicating a large number of negatively charged cell membranes; altering the molecular structure of the cell membrane; increasing the permeability of the cell membrane; and causing cytoplasmic diffusion and cell lysis, resulting in lethal activity against most bacteria. The synthesised molecules were characterised by 1H NMR and mass spectrometry. The strong specific interaction of the boronic acid moiety with the surface of E. coli and the electrostatic interaction of the quaternary amine salt with the cell membrane were confirmed by antibacterial experiments on molecules with and without the targeting moiety. The targeting group-modified micelles enhanced the antibacterial effect of the micelles very effectively through specific interactions and electrostatic interactions. In addition, in vitro skin wound healing experiments also confirmed the targeting and antimicrobial effect of micelles. These results suggest that the specific release of nitric oxide at the site of bacterial infection is an important guide to further address the emergence of antibiotic-resistant strains of bacteria. Full article
(This article belongs to the Special Issue Polymers and Drug Delivery)
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24 pages, 960 KiB  
Review
Polymeric Nanoparticles for Inhaled Vaccines
by Nusaiba K. Al-Nemrawi, Ruba S. Darweesh, Lubna A. Al-shriem, Farah S. Al-Qawasmi, Sereen O. Emran, Areej S. Khafajah and Muna A. Abu-Dalo
Polymers 2022, 14(20), 4450; https://doi.org/10.3390/polym14204450 - 21 Oct 2022
Cited by 8 | Viewed by 2578
Abstract
Many recent studies focus on the pulmonary delivery of vaccines as it is needle-free, safe, and effective. Inhaled vaccines enhance systemic and mucosal immunization but still faces many limitations that can be resolved using polymeric nanoparticles (PNPs). This review focuses on the use [...] Read more.
Many recent studies focus on the pulmonary delivery of vaccines as it is needle-free, safe, and effective. Inhaled vaccines enhance systemic and mucosal immunization but still faces many limitations that can be resolved using polymeric nanoparticles (PNPs). This review focuses on the use of properties of PNPs, specifically chitosan and PLGA to be used in the delivery of vaccines by inhalation. It also aims to highlight that PNPs have adjuvant properties by themselves that induce cellular and humeral immunogenicity. Further, different factors influence the behavior of PNP in vivo such as size, morphology, and charge are discussed. Finally, some of the primary challenges facing PNPs are reviewed including formulation instability, reproducibility, device-related factors, patient-related factors, and industrial-level scale-up. Herein, the most important variables of PNPs that shall be defined in any PNPs to be used for pulmonary delivery are defined. Further, this study focuses on the most popular polymers used for this purpose. Full article
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17 pages, 12109 KiB  
Article
Cefazolin Loaded Oxidized Regenerated Cellulose/Polycaprolactone Bilayered Composite for Use as Potential Antibacterial Dural Substitute
by Arunnee Sanpakitwattana, Waraporn Suvannapruk, Sorayouth Chumnanvej, Ruedee Hemstapat and Jintamai Suwanprateeb
Polymers 2022, 14(20), 4449; https://doi.org/10.3390/polym14204449 - 21 Oct 2022
Cited by 8 | Viewed by 1773
Abstract
Oxidized regenerated cellulose/polycaprolactone bilayered composite (ORC/PCL bilayered composite) was investigated for use as an antibacterial dural substitute. Cefazolin at the concentrations of 25, 50, 75 and 100 mg/mL was loaded in the ORC/PCL bilayered composite. Microstructure, density, thickness, tensile properties, cefazolin loading content, [...] Read more.
Oxidized regenerated cellulose/polycaprolactone bilayered composite (ORC/PCL bilayered composite) was investigated for use as an antibacterial dural substitute. Cefazolin at the concentrations of 25, 50, 75 and 100 mg/mL was loaded in the ORC/PCL bilayered composite. Microstructure, density, thickness, tensile properties, cefazolin loading content, cefazolin releasing profile and antibacterial activity against S. aureus were measured. It was seen that the change in concentration of cefazolin loading affected the microstructure of the composite on the rough side, but not on the dense or smooth side. Cefazolin loaded ORC/PCL bilayered composite showed greater densities, but lower thickness, compared to those of drug unloaded composite. Tensile modulus was found to be greater and increased with increasing cefazolin loading, but tensile strength and strain at break were lower compared to the drug unloaded composite. In vitro cefazolin release in artificial cerebrospinal fluid (aCSF) consisted of initial burst release on day 1, followed by a constant small release of cefazolin. The antibacterial activity was observed to last for up to 4 days depending on the cefazolin loading. All these results suggested that ORC/PCL bilayered composite could be modified to serve as an antibiotic carrier for potential use as an antibacterial synthetic dura mater. Full article
(This article belongs to the Special Issue Polymer Materials for Drug Delivery and Tissue Engineering)
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36 pages, 5442 KiB  
Review
On the Use of Polymer-Based Composites for the Creation of Optical Sensors: A Review
by Pavel Melnikov, Alexander Bobrov and Yuriy Marfin
Polymers 2022, 14(20), 4448; https://doi.org/10.3390/polym14204448 - 21 Oct 2022
Cited by 18 | Viewed by 3041
Abstract
Polymers are widely used in many areas, but often their individual properties are not sufficient for use in certain applications. One of the solutions is the creation of polymer-based composites and nanocomposites. In such materials, in order to improve their properties, nanoscale particles [...] Read more.
Polymers are widely used in many areas, but often their individual properties are not sufficient for use in certain applications. One of the solutions is the creation of polymer-based composites and nanocomposites. In such materials, in order to improve their properties, nanoscale particles (at least in one dimension) are dispersed in the polymer matrix. These properties include increased mechanical strength and durability, the ability to create a developed inner surface, adjustable thermal and electrical conductivity, and many others. The materials created can have a wide range of applications, such as biomimetic materials and technologies, smart materials, renewable energy sources, packaging, etc. This article reviews the usage of composites as a matrix for the optical sensors and biosensors. It highlights several methods that have been used to enhance performance and properties by optimizing the filler. It shows the main methods of combining indicator dyes with the material of the sensor matrix. Furthermore, the role of co-fillers or a hybrid filler in a polymer composite system is discussed, revealing the great potential and prospect of such matrixes in the field of fine properties tuning for advanced applications. Full article
(This article belongs to the Special Issue Synthesis and Applications of Polymer-Based Nanocomposites)
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16 pages, 4481 KiB  
Article
Nanofiber-Based Odor-Free Medical Mask Fabrication Using Polyvinyl Butyral and Eucalyptus Anti Odor Agent
by Jean-Sebastien Benas, Ching-Ya Huang, Zhen-Li Yan, Fang-Cheng Liang, Po-Yu Li, Chen-Hung Lee, Yang-Yen Yu, Chin-Wen Chen and Chi-Ching Kuo
Polymers 2022, 14(20), 4447; https://doi.org/10.3390/polym14204447 - 20 Oct 2022
Cited by 5 | Viewed by 2094
Abstract
Following the 2020 COVID-19 worldwide outbreak, many countries adopted sanitary and safety measures to safeguard public health such as wearing medical face mask. While face masks became a necessity for people, disadvantages impede their long period wearing such as uncomfortable breathability and odor. [...] Read more.
Following the 2020 COVID-19 worldwide outbreak, many countries adopted sanitary and safety measures to safeguard public health such as wearing medical face mask. While face masks became a necessity for people, disadvantages impede their long period wearing such as uncomfortable breathability and odor. The intermediate layer of the medical face mask is composed of porous non-woven fabric to block external particles while maintaining breathability. To overcome aforementioned limitation, this study uses electrospinning to design and fabricate odorless face masks via the use of aromatic oil. Eucalyptus essential oil is encapsulated through mixing and layer-by-layer by hydrophobic polyvinyl butyral and further used to fabricate the medical mask intermediate layer. We found that adding 0.2 g of eucalyptus into polyvinyl butyral fabric through mixing results in the deodorization rate of 80% after 2 h, with fabric thickness of 440.9 μm, and melt-blown non-woven fabric thickness of 981.7 μm. The Particle Filtration Efficiency of 98.3%, Bacterial Filtration Efficiency above 99.9%, and the differential pressure of 4.7 mm H2O/cm2 meet the CNS 14774 standard on medical face masks. Therefore, this study successfully proved that this type of masks’ middle layer not only effectively protects against coronavirus, but also provides better scents and makes it more comfortable for consumers. Full article
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14 pages, 3050 KiB  
Article
Design of Nanohydroxyapatite/Pectin Composite from Opuntia Ficus-Indica Cladodes for the Management of Microbial Infections
by N. Saidi, K. Azzaoui, M. Ramdani, E. Mejdoubi, N. Jaradat, S. Jodeh, B. Hammouti, R. Sabbahi and A. Lamhamdi
Polymers 2022, 14(20), 4446; https://doi.org/10.3390/polym14204446 - 20 Oct 2022
Cited by 5 | Viewed by 1550
Abstract
Hydroxyapatite (HAp) attracts interest as a biomaterial for use in bone substitution or allografts. In the current work, biomaterial nanocomposites based on HAp and pectin were synthesized by using the double decomposition method, which involved using pectin extracted from fresh cladodes of the [...] Read more.
Hydroxyapatite (HAp) attracts interest as a biomaterial for use in bone substitution or allografts. In the current work, biomaterial nanocomposites based on HAp and pectin were synthesized by using the double decomposition method, which involved using pectin extracted from fresh cladodes of the prickly pear, Opuntia ficus-indica. The crystallinity, purity, and several analytical techniques like Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy were used to understand the surface’s shape. The results revealed that the produced HAp/pectin nanoparticles are pure, spherical, and amorphous. The spectroscopic data indicated a substantial interaction between HAp and pectin, specifically between Ca (II) and pectin hydroxyl and carboxyl groups. The presence of pectin showed a noticeable influence on the prepared nanocomposite texture and porosity. We further assess the antibacterial and antifungal activity of the developed nanocomposite against a number of pathogenic bacteria and fungi, evaluated by the well diffusion method. In the absence of pectin, the XRD analysis revealed that the HAp nanoparticles had 10.93% crystallinity. When the pectin concentration reached 10 wt.%, it was reduced to approximately 7.29%. All synthesized nanocomposites demonstrated strong antimicrobial activity against both Gram-positive (Staphylococcus aureus and Bacillus cereus) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria in addition to various fungi (e.g., Aspergillus fumigatus, Penicillium funiculosum, and Trichoderma viride). This study endorses the HAp/Pectin nanocomposite as an efficient antimicrobial material for biomedical advanced applications. Full article
(This article belongs to the Special Issue Polymer Materials from Natural Resources)
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19 pages, 3853 KiB  
Article
Electrochemical Performance of Biopolymer-Based Hydrogel Electrolyte for Supercapacitors with Eco-Friendly Binders
by Giovanni Landi, Luca La Notte, Alessandro Lorenzo Palma and Giovanni Puglisi
Polymers 2022, 14(20), 4445; https://doi.org/10.3390/polym14204445 - 20 Oct 2022
Cited by 9 | Viewed by 2369
Abstract
An environmentally friendly hydrogel based on gelatin has been investigated as a gel polymer electrolyte in a symmetric carbon-based supercapacitor. To guarantee the complete sustainability of the devices, biomaterials from renewable resources (such as chitosan, casein and carboxymethyl cellulose) and activated carbon (from [...] Read more.
An environmentally friendly hydrogel based on gelatin has been investigated as a gel polymer electrolyte in a symmetric carbon-based supercapacitor. To guarantee the complete sustainability of the devices, biomaterials from renewable resources (such as chitosan, casein and carboxymethyl cellulose) and activated carbon (from coconut shells) have been used as a binder and filler within the electrode, respectively. The electrochemical properties of the devices have been compared by using cyclic voltammetry, galvanostatic charge/discharge curves and impedance spectroscopy. Compared to the liquid electrolyte, the hydrogel supercapacitors show similar energy performance with an enhancement of stability up to 12,000 cycles (e.g., chitosan as a binder). The most performant device can deliver ca. 5.2 Wh/kg of energy at a high power density of 1256 W/kg. A correlation between the electrochemical performances and charge storage mechanisms (involving faradaic and non-faradaic processes) at the interface electrode/hydrogel has been discussed. Full article
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16 pages, 4227 KiB  
Article
Potential of Alpha-Mangostin-Loaded PLGA Nanoparticles for Cholangiocarcinoma Treatment
by Asma Tahir, Tullayakorn Plengsuriyakarn, Chuda Chittasupho and Kesara Na-Bangchang
Polymers 2022, 14(20), 4444; https://doi.org/10.3390/polym14204444 - 20 Oct 2022
Cited by 1 | Viewed by 1513
Abstract
Alpha-mangostin (AM), a significant component isolated from the pericarp of mangosteen (Garcinia mangostana L.), has been demonstrated as a potential compound for the treatment of cholangiocarcinoma (CCA). Due to its hydrophobic nature, however, its clinical uses may be limited by its low [...] Read more.
Alpha-mangostin (AM), a significant component isolated from the pericarp of mangosteen (Garcinia mangostana L.), has been demonstrated as a potential compound for the treatment of cholangiocarcinoma (CCA). Due to its hydrophobic nature, however, its clinical uses may be limited by its low aqueous solubility, poor stability, and low bioavailability. The present study aimed to formulate and characterize the AM-loaded PLGA nanoparticles (AM-PLGA-NPs) and further evaluate the antiproliferative and proapoptotic activities, including the inhibitory activities on CCA cell (CL-6 and HuCCT-1) invasion and migration. The AM-PLGA-NPs were prepared using PLGA MW 7000–17,000 and 38,000–54,000 by the solvent displacement method. The methods used to evaluate these activities included a MTT assay, flow-cytometry, QCM ECMatrix cell migration, and cell invasion assays, respectively. The optimized AM-PLGA-NPs were characterized for physical (particle size and morphology, polydispersity index, and zeta potential) and pharmaceutical (encapsulation efficiency, loading efficiency, and drug release profile) parameters. AM-PLGA-NPs showed relatively potent and selective antiproliferative and proapoptotic activities in both CCA cell lines in a concentration- and time-dependent manner. The results revealed that the PLGA nanoparticles could be a suitable nanocarrier to encapsulate AM for its delivery to the CCA cells. Full article
(This article belongs to the Section Polymer Applications)
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15 pages, 2896 KiB  
Article
Preparation of Crystal Violet Lactone Complex and Its Effect on Discoloration of Metal Surface Coating
by Wenbo Li, Xiaoxing Yan and Wenting Zhao
Polymers 2022, 14(20), 4443; https://doi.org/10.3390/polym14204443 - 20 Oct 2022
Cited by 11 | Viewed by 1797
Abstract
In this paper, a thermochromic complex was prepared from crystal violet lactone (CVL), bisphenol A (BPA) and tetradecanol. The color-changing temperature of the color-changing compound was found to be 25 °C by orthogonal experiment. Microcapsules coated with a thermochromic compound were added into [...] Read more.
In this paper, a thermochromic complex was prepared from crystal violet lactone (CVL), bisphenol A (BPA) and tetradecanol. The color-changing temperature of the color-changing compound was found to be 25 °C by orthogonal experiment. Microcapsules coated with a thermochromic compound were added into alkyd resin at different mass concentrations. With the increase in temperature and mass fraction of microcapsules in the coating, the color difference of the coating showed an upward trend. The highest variation in the coating’s color difference occurs when there were 10% microcapsules. When the mass fraction of microcapsules was 15.0~25.0%, there was little change to the gloss of the coating. With the increase in the mass fraction of the coating microcapsules, the hardness of the coating gradually increased. The hardness was at its best when the microcapsule concentration was 25%. When the microcapsule concentration was 20%, the impact resistance of the coating was at its best. The coating had good cold-liquid resistance to acetic acid, ethanol, and NaCl solutions, and there was basically no mark on the coating surface before and after the cold-liquid-resistance test. The addition of microcapsules did not change the chemical composition of the coating, and it improved the performance of the coating. When the microcapsule concentration was 10%, the overall performance of the coating was at its best, which laid the technical foundation for thermochromic coating on the metal surface. Full article
(This article belongs to the Special Issue Polymers and Nanotechnology for Industry 4.0)
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15 pages, 3700 KiB  
Article
Characterisation of Films Based on Exopolysaccharides from Alteromonas Strains Isolated from French Polynesia Marine Environments
by Patrícia Concórdio-Reis, João R. Pereira, Vítor D. Alves, Ana R. Nabais, Luísa A. Neves, Ana C. Marques, Elvira Fortunato, Xavier Moppert, Jean Guézennec, Maria A.M. Reis and Filomena Freitas
Polymers 2022, 14(20), 4442; https://doi.org/10.3390/polym14204442 - 20 Oct 2022
Cited by 1 | Viewed by 1715
Abstract
This work assessed the film-forming capacity of exopolysaccharides (EPS) produced by six Alteromonas strains recently isolated from different marine environments in French Polynesia atolls. The films were transparent and resulted in small colour alterations when applied over a coloured surface (ΔEab [...] Read more.
This work assessed the film-forming capacity of exopolysaccharides (EPS) produced by six Alteromonas strains recently isolated from different marine environments in French Polynesia atolls. The films were transparent and resulted in small colour alterations when applied over a coloured surface (ΔEab below 12.6 in the five different colours tested). Moreover, scanning electron microscopy showed that the EPS films were dense and compact, with a smooth surface. High water vapour permeabilities were observed (2.7–6.1 × 10−11 mol m−1 s−1 Pa−1), which are characteristic of hydrophilic polysaccharide films. The films were also characterised in terms of barrier properties to oxygen and carbon dioxide. Interestingly, different behaviours in terms of their mechanical properties under tensile tests were observed: three of the EPS films were ductile with high elongation at break (ε) (35.6–47.0%), low tensile strength at break (Ꞇ) (4.55–11.7 MPa) and low Young’s modulus (εm) (10–93 MPa), whereas the other three were stiffer and more resistant with a higher Ꞇ (16.6–23.6 MPa), lower ε (2.80–5.58%), and higher εm (597–1100 MPa). These properties demonstrate the potential of Alteromonas sp. EPS films to be applied in different areas such as biomedicine, pharmaceuticals, or food packaging. Full article
(This article belongs to the Special Issue Biodegradable Polymer Composites: Fabrication and Applications)
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22 pages, 796 KiB  
Review
A Review: Using Multiple Templates for Molecular Imprinted Polymer: Is It Good?
by Niky Murdaya, Anastasya Leatemia Triadenda, Driyanti Rahayu and Aliya Nur Hasanah
Polymers 2022, 14(20), 4441; https://doi.org/10.3390/polym14204441 - 20 Oct 2022
Cited by 17 | Viewed by 3336
Abstract
A multi-template molecularly imprinting polymer (MT-MIP) strategy has been proposed and is increasingly utilised to synthesise MIP with multiple recognition sites in a single polymer using multiple target species as templates. This approach can expand MIP applications for simultaneous recognition and extraction of [...] Read more.
A multi-template molecularly imprinting polymer (MT-MIP) strategy has been proposed and is increasingly utilised to synthesise MIP with multiple recognition sites in a single polymer using multiple target species as templates. This approach can expand MIP applications for simultaneous recognition and extraction of more than one analyte. The advantages of MT-MIP are simultaneous analyte extraction in one process, lower solvent consumption, cost-effectiveness, and short analysis time. The use of multiple templates to prepare a MIP reduces the effort required to prepare different MIPs for different analytes separately. Although there are many studies about developing MT-MIP, there are no review articles that discuss the success rate of MT-MIP. Therefore, in this review, we summarise MT-MIP synthesis, including the polymerisation method being used, the important factors that affect the quality of MT-MIP, and MT-MIP applications. MT-MIP has great potential in chemical isolation and analysis. MT-MIP produces a product that has good sensitivity, selectivity, and reusability. Furthermore, many templates, functional monomers, and crosslinkers can be formulated as MT-MIP and have a high success rate. This is evidenced by the good values of the maximum absorption capacity (Qmax), imprinting factor (IF), and reusability. We expect that the evidence presented in this review can encourage additional research on the development and application of MT-MIP. Full article
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17 pages, 3143 KiB  
Article
Clay-Alginate Beads Loaded with Ionic Liquids: Potential Adsorbents for the Efficient Extraction of Oil from Produced Water
by Shehzad Liaqat, Taleb H. Ibrahim, Mustafa I. Khamis, Paul Nancarrow and Mohamed Yehia Abouleish
Polymers 2022, 14(20), 4440; https://doi.org/10.3390/polym14204440 - 20 Oct 2022
Cited by 1 | Viewed by 1475
Abstract
Produced water (PW) generated from the petroleum industry, during the extraction of oil and gas, has harmful impacts on human health and aquatic life, due to its complex nature. Therefore, it is necessary to treat it before discharging it into the environment in [...] Read more.
Produced water (PW) generated from the petroleum industry, during the extraction of oil and gas, has harmful impacts on human health and aquatic life, due to its complex nature. Therefore, it is necessary to treat it before discharging it into the environment in order to avoid serious environmental concerns. In this research, oil adsorption from PW was investigated using clay-alginate beads loaded with ionic liquids (ILs), as the adsorbent material. The effects of several process parameters, such as the initial concentration of oil, contact time, pH, and temperature on the removal efficiency of the beads, were analyzed and optimized. Different characterization methods, such as the Fourier transform infrared spectrophotometer (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and thermal gravimetric analysis (TGA), were used to investigate the surface morphology, the chemical bond structure and functional group, and the thermal stability of the ILs-based beads. The results revealed that the clay-alginate-ILs beads indicated a removal efficiency of 71.8% at the optimum conditions (600 ppm initial oil concentration, 70 min contact time, 10 pH, and at room temperature) with an adsorption capacity of 431 mg/g. The FTIR analysis confirmed the successful chemical bond interaction of the oil with the beads. The SEM analysis verified that the beads have a porous and rough surface, which is appropriate for the adsorption of oil onto the bead’s surface. The TGA analysis provides the thermal degradation profile for the clay-alginate-ILs. The beads used in the adsorption process were regenerated and used for up to four cycles. Full article
(This article belongs to the Special Issue Smart Natural-Based Polymers)
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16 pages, 3767 KiB  
Article
Mechanical Properties of High Temperature Vulcanized Silicone Rubber Aged in the Natural Environment
by Zhijin Zhang, Jianjie Zhao, Xiaodong Wan, Xingliang Jiang and Jianlin Hu
Polymers 2022, 14(20), 4439; https://doi.org/10.3390/polym14204439 - 20 Oct 2022
Cited by 7 | Viewed by 2297
Abstract
Composite insulators operate in harsh field environments all year round. Their various properties and states of aging require attention. It is important to study the performance changes of composite insulator sheds after aging to evaluate the life of insulators operating on grids. For [...] Read more.
Composite insulators operate in harsh field environments all year round. Their various properties and states of aging require attention. It is important to study the performance changes of composite insulator sheds after aging to evaluate the life of insulators operating on grids. For this reason, 22 composite insulator sheds from different factories, with different voltage levels and different ages years were selected to conduct mechanical properties testing. The mechanical properties include hardness, tensile strength, and elongation at break, and were investigated by thermogravimetric (TGA) testing, surface morphology, and nuclear magnetic resonance (NMR) characterization. The changes in mechanical properties of high temperature vulcanization (HTV) composite insulator silicone rubber aged in the natural environment were analyzed, including the reasons for these changes. The results showed that the transverse relaxation time T2 of the sample was closely related to its aging state. The more serious the silicone rubber’s aging, the smaller was the T2. The state of the composite insulator can be evaluated by using T2 and aging years simultaneously. With the actual degree of aging in the silicone rubber intensified, its tensile strength and elongation at break generally showed a downward trend. Full article
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15 pages, 2711 KiB  
Article
Mechanical Amorphization of Chitosan with Different Molecular Weights
by Ekaterina Podgorbunskikh, Timofei Kuskov, Denis Rychkov, Oleg Lomovskii and Aleksey Bychkov
Polymers 2022, 14(20), 4438; https://doi.org/10.3390/polym14204438 - 20 Oct 2022
Cited by 11 | Viewed by 4306
Abstract
Mechanical amorphization of three chitosan samples with high, medium, and low molecular weight was studied. It is shown that there are no significant differences between the course of amorphization process in a planetary ball mill of chitosan with different molecular weights, and the [...] Read more.
Mechanical amorphization of three chitosan samples with high, medium, and low molecular weight was studied. It is shown that there are no significant differences between the course of amorphization process in a planetary ball mill of chitosan with different molecular weights, and the maximum degree of amorphization was achieved in 600 s of high intensity mechanical action. Specific energy consumption was 28 kJ/g, being comparable to power consumption for amorphization of cellulose determined previously (29 kJ/g) and 5–7-fold higher than that for amorphization of starch (4–6 kJ/g). Different techniques for determining the crystallinity index (CrI) of chitosan (analysis of the X-ray diffraction (XRD) data, the peak height method, the amorphous standard method, peak deconvolution, and full-profile Rietveld analysis) were compared. The peak height method is characterized by a broader working range but provides deviated CrI values. The peak deconvolution method (with the amorphous Voigt function) makes it possible to calculate the crystallinity index of chitosan with greater accuracy, but the analysis becomes more difficult with samples subjected to mechanical processing. In order to refine the structure and calculation of CrI by the Rietveld method, an attempt to optimize the structure file by the density functional theory (DFT) method was performed. The averaged profile of amorphous chitosan approximated by an eighth-order Fourier model improved the correctness of the description of the amorphous contribution for XRD data processing. The proposed equation may be used as a universal standard model of amorphous chitosan to determine the crystallinity index both for the amorphous standard method and for peak deconvolution of XRD patterns for arbitrary chitosan samples. Full article
(This article belongs to the Special Issue Polymers in Food Science)
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