Special Issue "Smart and Functional Elastomers, Hydrogels, and Ionogels"

A special issue of Polymers (ISSN 2073-4360).

Deadline for manuscript submissions: closed (31 October 2018)

Special Issue Editor

Guest Editor
Prof. Hyun-Joong Chung

Department of Chemical and Materials Engineering, Faculty of Engineering, University of Alberta, Edmonton, AB, Canada
Website | E-Mail
Interests: soft materals; hydrogels; elastomers; bioelectronics; energy storage materials

Special Issue Information

Dear Colleagues,

This Special Issue focus on the current state-of-the-art of the fundamentals and applications of elastomers, hydrogels, and ionogels.  These polymeric materials, either in dried or in swollen states, exhibit soft and resilient mechanical properties, often with great fracture toughness.  Incorporation of functional groups or nanoparticles adds novel functionality or stimuli-responsiveness on top of their their unique mechanical properties, enabling a broad range of potential applications such as flexible or stretchable energy storage, biosensors and biomaterials, soft electronics, and many more.

Papers are sought that discuss the latest research in the area or summarize selected areas of the field. The scope of the Special Issue encompasses the synthesis, characterization, and application of elastomers and gels made of conjugated polymers, organic radical polymers, ion-conducting polymers, metal-containing polymers, or hybrid inorganic/organic motifs.

Of particular interests are on the structure-property relations of these polymeric materials, or on the novel chemistry routes to enable functionalities in these materials, or on their applications on energy and biomedical researches as a stepping stone to an interdisciplinary research.

Prof. Hyun-Joong Chung
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Elastomers
  • Hydrogels
  • Ionogels
  • Functional polymer
  • Smart materials
  • Electroactive polymer
  • Electroactive gels
  • Conjugated polymer
  • Polyelectrolyte
  • Metal-containing polymer
  • Composite
  • Energy storage
  • Batteries
  • Capacitors
  • Electrochemical transistors
  • Ion sensing transistors
  • Sensors

Published Papers (12 papers)

View options order results:
result details:
Displaying articles 1-12
Export citation of selected articles as:

Research

Jump to: Review

Open AccessArticle Fabrication of Phosphate-Imprinted PNIPAM/SiO2 Hybrid Particles and Their Phosphate Binding Property
Polymers 2019, 11(2), 253; https://doi.org/10.3390/polym11020253
Received: 24 October 2018 / Revised: 29 January 2019 / Accepted: 30 January 2019 / Published: 2 February 2019
PDF Full-text (3160 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A SiO2 microsphere imprinted by phosphate ions was prepared with the use of phosphate ion as the template molecule and tetraethoxysilane as the precursor. Thereafter, the imprinted SiO2 microspheres were modified with 3-(trimethoxysilyl)propyl methacrylate ([email protected]2), followed by introducing the [...] Read more.
A SiO2 microsphere imprinted by phosphate ions was prepared with the use of phosphate ion as the template molecule and tetraethoxysilane as the precursor. Thereafter, the imprinted SiO2 microspheres were modified with 3-(trimethoxysilyl)propyl methacrylate ([email protected]2), followed by introducing the double bond. In the presence of [email protected]2, using N-isopropylacrylamide as monomer, and potassium persulfate as initiator, polymer/inorganic hybrid particles (PNIPAM/SiO2) were prepared. Fourier transform infrared spectroscopy, thermogravimetric analysis, nitrogen adsorption-desorption test, and transmission electron microscope were employed for the characterization of molecular imprinted SiO2 microspheres and PNIPAM/SiO2 hybrid particles. The effects of phosphate concentration, pH value, and adsorption temperature on the phosphate binding properties of PNIPAM/SiO2 hybrid particles were studied by UV-vis spectrophotometer. The experimental results shed light on the fact that the PNIPAM structure is beneficial for the improvement of the adsorption ability of phosphate-imprinted SiO2 microspheres. With the increase in the initial phosphate concentration, the adsorption capacity of hybrid particles to phosphate ions increased to 274 mg/g at pH = 7 and 15 °C. The acid condition and the temperature below the low critical solution temperature (LCST) of PNIPAM are favorable to the adsorption of phosphate ions by PNIPAM/SiO2 hybrid particles, and the maximum adsorption capacity can reach 287 mg/g (at pH = 5 and 15 °C). The phosphate imprinted polymer/inorganic hybrid material is expected to be put to use in the fields of phosphate ions adsorption, separation, and recovery. Full article
(This article belongs to the Special Issue Smart and Functional Elastomers, Hydrogels, and Ionogels)
Figures

Graphical abstract

Open AccessArticle The Effect of the Surface Area of Carbon Black Grades on HNBR in Harsh Environments
Polymers 2019, 11(1), 61; https://doi.org/10.3390/polym11010061
Received: 5 December 2018 / Revised: 18 December 2018 / Accepted: 28 December 2018 / Published: 4 January 2019
PDF Full-text (6219 KB) | HTML Full-text | XML Full-text
Abstract
Concerning the still rising demand for oil and gas products, the development of new reliable materials to guarantee the facility safety at extreme operating conditions is an utmost necessity. The present study mainly deals with the influence of different carbon black (CB) filled [...] Read more.
Concerning the still rising demand for oil and gas products, the development of new reliable materials to guarantee the facility safety at extreme operating conditions is an utmost necessity. The present study mainly deals with the influence of different carbon black (CB) filled hydrogenated nitrile butadiene rubber (HNBR), which is a material usually used in sealing applications, on the rapid gas decompression (RGD) resistance in harsh environments. Therefore, RGD component level tests were conducted in an autoclave. The supporting mechanical and dynamic mechanical property analysis, the microscopic level investigations on the material and failure analysis were conducted and are discussed in this work. Under the tested conditions, the samples filled with smaller CB primary particles showed a slightly lower volume increase during the compression and decompression phases; however, they steered to a significantly lower resistance to RGD. Transmission electron micrographs revealed that the samples filled with smaller CB particles formed larger structures as well as densified filler networks including larger agglomerates and as a consequence a decrease effective matrix component around the CB particles. Apparently, at higher loading conditions, which already deliver a certain level of mechanical stresses and strains, the densified filler network, and especially a lower amount of effective matrix material composition, adversely affect the RGD resistance. SEM-based fracture analysis did not identify any influence of the CB grades tested on the crack initiation site; however, it revealed that the cracks initiated from existing voids, hard particles, or low strength matrix sites and propagated to the outer surface. Full article
(This article belongs to the Special Issue Smart and Functional Elastomers, Hydrogels, and Ionogels)
Figures

Graphical abstract

Open AccessArticle Self-Healing Cellulose Nanocrystals-Containing Gels via Reshuffling of Thiuram Disulfide Bonds
Polymers 2018, 10(12), 1392; https://doi.org/10.3390/polym10121392
Received: 16 November 2018 / Revised: 12 December 2018 / Accepted: 12 December 2018 / Published: 15 December 2018
PDF Full-text (2745 KB) | HTML Full-text | XML Full-text
Abstract
Self-healing gels based on reshuffling disulfide bonds have attracted great attention due to their ability to restore structure and mechanical properties after damage. In this work, self-healing gels with different cellulose nanocrystals (CNC) contents were prepared by embedding the thiuram disulfide bonds into [...] Read more.
Self-healing gels based on reshuffling disulfide bonds have attracted great attention due to their ability to restore structure and mechanical properties after damage. In this work, self-healing gels with different cellulose nanocrystals (CNC) contents were prepared by embedding the thiuram disulfide bonds into gels via polyaddition. By the reshuffling of thiuram disulfide bonds, the CNC-containing gels repair the crack and recover mechanical properties rapidly under visible light in air. The thiuram disulfide-functionalized gels with a CNC content of 2.2% are highly stretchable and can be stretched approximately 42.6 times of their original length. Our results provide useful approaches for the preparation of dynamic CNC-containing gels with implications in many related engineering applications. Full article
(This article belongs to the Special Issue Smart and Functional Elastomers, Hydrogels, and Ionogels)
Figures

Graphical abstract

Open AccessArticle Optimizing the Energy Harvesting Cycle of a Dissipative Dielectric Elastomer Generator for Performance Improvement
Polymers 2018, 10(12), 1341; https://doi.org/10.3390/polym10121341
Received: 28 October 2018 / Revised: 30 November 2018 / Accepted: 1 December 2018 / Published: 4 December 2018
PDF Full-text (4988 KB) | HTML Full-text | XML Full-text
Abstract
This paper optimizes the energy harvesting cycle of dissipative dielectric elastomer generators (DEGs) to explore possible approaches for improving the energy harvesting performance. By utilizing the developed theoretical framework, the dissipative performance of the DEG with a constant voltage cycle is analyzed, which [...] Read more.
This paper optimizes the energy harvesting cycle of dissipative dielectric elastomer generators (DEGs) to explore possible approaches for improving the energy harvesting performance. By utilizing the developed theoretical framework, the dissipative performance of the DEG with a constant voltage cycle is analyzed, which shows good agreement with the existing experimental data. On this basis, we design a novel energy harvesting cycle and a corresponding energy harvesting circuit in which a transfer capacitor is utilized to store the charge transferred from the DEG. Then, the energy conversion performance of the DEG with the novel energy harvesting cycle is investigated. The results indicate that both the energy density and conversion efficiency are improved by choosing a high voltage during the discharging process and that as the R-C time constant increases, the enhancement effect of the voltage increases and then approaches to the saturation. In addition, there is an optimal transfer capacitor that can maximize energy density or conversion efficiency, and the optimal transfer capacitor increases with the increase in the R-C time constant. These results and methods are expected to guide the optimal design and assessment of DEGs. Full article
(This article belongs to the Special Issue Smart and Functional Elastomers, Hydrogels, and Ionogels)
Figures

Figure 1

Open AccessArticle Smart Shear-Thinning Hydrogels as Injectable Drug Delivery Systems
Polymers 2018, 10(12), 1317; https://doi.org/10.3390/polym10121317
Received: 30 October 2018 / Revised: 22 November 2018 / Accepted: 22 November 2018 / Published: 28 November 2018
PDF Full-text (2148 KB) | HTML Full-text | XML Full-text
Abstract
In this study, we fabricated and characterized a smart shear-thinning hydrogel composed of gelatin and laponite for localized drug delivery. We added chitosan (Chi) and poly N-isopropylacrylamide-co-Acrylic acid (PNIPAM) particles to the shear-thinning gel to render it pH-responsive. The effects [...] Read more.
In this study, we fabricated and characterized a smart shear-thinning hydrogel composed of gelatin and laponite for localized drug delivery. We added chitosan (Chi) and poly N-isopropylacrylamide-co-Acrylic acid (PNIPAM) particles to the shear-thinning gel to render it pH-responsive. The effects of total solid weight and the percentage of laponite in a solid mass on the rheological behavior and mechanical properties were investigated to obtain the optimum formulation. The nanocomposite gel and particles were characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), zeta potential, and dynamic light scattering techniques. Finally, release related experiment including degradability, swelling and Rhodamine B (Rd) release at various pH were performed. The results suggest that incorporation of silicate nanoplatelets in the gelatin led to the formation of the tunable porous composite, with a microstructure that was affected by introducing particles. Besides, the optimum formulation possessed shear-thinning properties with modified rheological and mechanical properties which preserved its mechanical properties while incubated in physiological conditions. The release related experiments showed that the shear-thinning materials offer pH-sensitive behavior so that the highest swelling ratio, degradation rate, and Rd release were obtained at pH 9.18. Therefore, this nanocomposite gel can be potentially used to develop pH-sensitive systems. Full article
(This article belongs to the Special Issue Smart and Functional Elastomers, Hydrogels, and Ionogels)
Figures

Figure 1

Open AccessArticle Multifunctional Ionogels Incorporated with Lanthanide (Eu3+, Tb3+) Complexes Covalently Modified Multi-Walled Carbon Nanotubes
Polymers 2018, 10(10), 1099; https://doi.org/10.3390/polym10101099
Received: 3 September 2018 / Revised: 24 September 2018 / Accepted: 2 October 2018 / Published: 5 October 2018
Cited by 1 | PDF Full-text (2347 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Ionogels refer to an emerging composite material made from the confinement of ionic liquids within some specific cross-linked network matrices. They have potential applications in areas such as electrochemical and optical-electric materials. Incorporation of lanthanide (Eu3+, Tb3+) complexes covalently [...] Read more.
Ionogels refer to an emerging composite material made from the confinement of ionic liquids within some specific cross-linked network matrices. They have potential applications in areas such as electrochemical and optical-electric materials. Incorporation of lanthanide (Eu3+, Tb3+) complexes covalently functionalized multi-walled carbon nanotubes (MWCNTs) in ionogels provide new ideas to design and synthesize novel luminescent hybrid materials that have excellent characteristics of luminescence and ionic conductivity. Here, the multifunctional ionogels were synthesized by confining an ionic liquid and the rare earth functionalized MWCNTs in the cross-linked polymethyl methacrylate (PMMA) networks, resulting in a novel optical/electric multifunctional hybrid material. The SEM images and digital photographs suggest that the lanthanide functionalized MWCNTs are evenly dispersed in the hybrid matrices, thus leading to a certain transparency bulky gel. The resulting ionogels exhibit certain viscosity and flexibility, and display an intense red/green emission under UV-light irradiation. The intrinsic conductibility of the embedded ionic liquids and carbon nanotubes in conjunction with the outstanding photoluminescent properties of lanthanide complexes makes the soft hybrid gels a material with great potential and valuable application in the field of optical-electric materials. Full article
(This article belongs to the Special Issue Smart and Functional Elastomers, Hydrogels, and Ionogels)
Figures

Figure 1

Open AccessArticle High-Strength Nanocomposite Hydrogels with Swelling-Resistant and Anti-Dehydration Properties
Polymers 2018, 10(9), 1025; https://doi.org/10.3390/polym10091025
Received: 2 July 2018 / Revised: 3 September 2018 / Accepted: 13 September 2018 / Published: 14 September 2018
PDF Full-text (4222 KB) | HTML Full-text | XML Full-text
Abstract
Hydrogels with excellent mechanical properties have potential for use in various fields. However, the swelling of hydrogels under water and the dehydration of hydrogels in air severely limits the practical applications of high-strength hydrogels due to the influence of air and water on [...] Read more.
Hydrogels with excellent mechanical properties have potential for use in various fields. However, the swelling of hydrogels under water and the dehydration of hydrogels in air severely limits the practical applications of high-strength hydrogels due to the influence of air and water on the mechanical performance of hydrogels. In this study, we report on a kind of tough and strong nanocomposite hydrogels (NC-G gels) with both swelling-resistant and anti-dehydration properties via in situ free radical copolymerization of acrylic acid (AA) and N-vinyl-2-pyrrolidone (VP) in the water-glycerol bi-solvent solutions containing small amounts of alumina nanoparticles (Al2O3 NPs) as the inorganic cross-linking agents. The topotactic chelation reactions between Al2O3 NPs and polymer matrix are thought to contribute to the cross-linking structure, outstanding mechanical performance, and swelling-resistant property of NC-G gels, whereas the strong hydrogen bonds between water and glycerol endow them with anti-dehydration capacity. As a result, the NC-G gels could maintain mechanical properties comparable to other as-prepared high-strength hydrogels when utilized both under water and in air environments. Thus, this novel type of hydrogel would considerably enlarge the application range of hydrogel materials. Full article
(This article belongs to the Special Issue Smart and Functional Elastomers, Hydrogels, and Ionogels)
Figures

Graphical abstract

Open AccessArticle Rhodamine-Functionalized Mechanochromic and Mechanofluorescent Hydrogels with Enhanced Mechanoresponsive Sensitivity
Polymers 2018, 10(9), 994; https://doi.org/10.3390/polym10090994
Received: 23 July 2018 / Revised: 3 September 2018 / Accepted: 3 September 2018 / Published: 6 September 2018
PDF Full-text (3713 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Smart materials responsible to external stimuli such as temperature, pH, solvents, light, redox agents, and mechanical or electric/magnetic field, have drawn considerable attention recently. Herein, we described a novel rhodamine (Rh) mechanophore-based mechanoresponsive micellar hydrogel with excellent mechanochromic and mechanofluorescent properties. We found [...] Read more.
Smart materials responsible to external stimuli such as temperature, pH, solvents, light, redox agents, and mechanical or electric/magnetic field, have drawn considerable attention recently. Herein, we described a novel rhodamine (Rh) mechanophore-based mechanoresponsive micellar hydrogel with excellent mechanochromic and mechanofluorescent properties. We found with astonishment that, due to the favorable activation of rhodamine spirolactam in the presence of water, together with the stress concentration effect, the mechanoresponsive sensitivity of this hydrogel was enhanced significantly. As a result, the stress needed to trigger the mechanochromic property of Rh in the hydrogel was much lower than in its native polymer matrix reported before. The hydrogel based on Rh, therefore, exhibited excellent mechanochromic property even at lower stress. Moreover, due to the reversibility of color on/off, the hydrogel based on Rh could be used as a reusable and erasable material for color printing/writing. Of peculiar importance is that the hydrogel could emit highly bright fluorescence under sufficient stress or strain. This suggested that the stress/strain of hydrogel could be detected quantificationally and effectively by the fluorescence data. We also found that the hydrogel could respond to acid/alkali and exhibited outstanding properties of acidichromism and acidifluorochromism. Up to now, hydrogels with such excellent mechanochromic and mechanofluorescent properties have rarely been reported. Our efforts may be essentially beneficial to the design of the mechanochromic and mechanofluorescent hydrogels with enhanced mechanoresponsive sensitivity, fostering their potential applications in a number of fields such as damage or stress/strain detection. Full article
(This article belongs to the Special Issue Smart and Functional Elastomers, Hydrogels, and Ionogels)
Figures

Graphical abstract

Open AccessArticle Thermosensitive Behavior and Super-Antibacterial Properties of Cotton Fabrics Modified with a Sercin-NIPAAm-AgNPs Interpenetrating Polymer Network Hydrogel
Polymers 2018, 10(8), 818; https://doi.org/10.3390/polym10080818
Received: 4 July 2018 / Revised: 24 July 2018 / Accepted: 24 July 2018 / Published: 25 July 2018
PDF Full-text (11721 KB) | HTML Full-text | XML Full-text
Abstract
Poly(N-isopropylacrylamide) (PNIPAAm), sericin (SS), and silver nitrate were combined to prepare an interpenetrating network (IPN) hydrogel having dual functions of temperature sensitivity and antibacterial properties. The structure and size of AgNPs in such an IPN hydrogel were characterized by the Fourier [...] Read more.
Poly(N-isopropylacrylamide) (PNIPAAm), sericin (SS), and silver nitrate were combined to prepare an interpenetrating network (IPN) hydrogel having dual functions of temperature sensitivity and antibacterial properties. The structure and size of AgNPs in such an IPN hydrogel were characterized by the Fourier Transform Infrared spectrum (FT-IR), X-ray powder diffraction (XRD) and Transmission Electron Microscope (TEM), and the thermal properties of the IPN hydrogel were characterized by Differential Scanning Calorimetry (DSC). Based on XRD patterns, Ag+ was successfully reduced to Ag0 by SS. It was observed by TEM that the particle size of silver particles was lower than 100 nm. The glass transition temperature (Tg) of IPN hydrogel was better than that of the PNIPAAm/AgNPs hydrogels, and lower critical solution temperature (LCST) values of the IPN hydrogel were obtained by DSC i.e. 31 °C. The thermal stability of the IPN hydrogel was successfully determined by the TGA. This IPN hydrogel was then used to modify the cotton fabrics by the “impregnation” method using glutaraldehyde (GA) as the cross-linking agent. The structures and properties of IPN hydrogel modified cotton fabric were characterized by scanning electron microscopy (SEM), FT-IR, and the thermogravimetry analysis (TGA). The results show that NIPAAm was successfully polymerized into PNIPAAm, and that there were neglected new groups in the hydrogel IPN. The IPN hydrogel was then successfully grafted onto cotton fabrics. SEM observations showed that the IPN hydrogel formed a membrane structure between the fibers, and improved the compactness of the fibers. At the temperature close to LCST (≈31 °C), the entire system was easily able to absorb water molecules. However, the hydrophilicity tended to decrease when the temperature was higher or lower than the LCST. The antibacterial rates of the modified cotton fabric against S. aureus and E. coli were as high as 99%. Full article
(This article belongs to the Special Issue Smart and Functional Elastomers, Hydrogels, and Ionogels)
Figures

Figure 1

Open AccessArticle High Performance Clean Fracturing Fluid Using a New Tri-Cationic Surfactant
Polymers 2018, 10(5), 535; https://doi.org/10.3390/polym10050535
Received: 20 April 2018 / Revised: 4 May 2018 / Accepted: 5 May 2018 / Published: 16 May 2018
Cited by 3 | PDF Full-text (3678 KB) | HTML Full-text | XML Full-text
Abstract
In order to improve the heat resistance of current clean fracturing fluids, a novel cationic surfactant (VES-T), composed of three single-chains and a spacer group, was designed and synthesized as thickener for the fluids. Various performances of such VES-T fluid in the presence [...] Read more.
In order to improve the heat resistance of current clean fracturing fluids, a novel cationic surfactant (VES-T), composed of three single-chains and a spacer group, was designed and synthesized as thickener for the fluids. Various performances of such VES-T fluid in the presence of NaSal were evaluated carefully. Study of the rheological properties demonstrated that the fluids with varying concentrations (3–5 wt %) of VES-T have excellent thermal stabilities under ultra-high temperatures ranging from 140 to 180 °C. Until now, this is the highest temperature that the VES fracturing fluid could bear. The VES-T/NaSal fluid exhibited good viscoelasticity and proppant-suspending capability, which was attributed to the three-dimensional network formed by entangled wormlike micelles. Furthermore, the VES fracturing fluids can be completely gel broken by standard brines within 2 h. Thus, the VES-T synthesized in this work has a good prospect for utilization during the development of ultra-high temperature reservoirs. Full article
(This article belongs to the Special Issue Smart and Functional Elastomers, Hydrogels, and Ionogels)
Figures

Graphical abstract

Open AccessArticle Influence of Ethylene Glycol Methacrylate to the Hydration and Transition Behaviors of Thermo-Responsive Interpenetrating Polymeric Network Hydrogels
Polymers 2018, 10(2), 128; https://doi.org/10.3390/polym10020128
Received: 31 December 2017 / Revised: 21 January 2018 / Accepted: 22 January 2018 / Published: 29 January 2018
Cited by 2 | PDF Full-text (11297 KB) | HTML Full-text | XML Full-text
Abstract
The influence of ethylene glycol methacrylate (EGMA) to the hydration and transition behaviors of thermo-responsive interpenetrating polymeric network (IPN) hydrogels containing sodium alginate, N-isopropylacrylamide (NIPAAm), and EGMA were investigated. The molar ratios of NIPAAm and EGMA were varied from 20:0 to 19.5:0.5 [...] Read more.
The influence of ethylene glycol methacrylate (EGMA) to the hydration and transition behaviors of thermo-responsive interpenetrating polymeric network (IPN) hydrogels containing sodium alginate, N-isopropylacrylamide (NIPAAm), and EGMA were investigated. The molar ratios of NIPAAm and EGMA were varied from 20:0 to 19.5:0.5 and 18.5:1.5 in the thermo-responsive alginate-Ca2+/P(NIPAAm-co-EGMA) IPN hydrogels. Due to the more hydrophilicity and high flexibility of EGMA, the IPN hydrogels exhibited higher lower critical solution temperature (LCST) and lower glass transition temperature (Tg) when the ratio of EGMA increases. The swelling/deswelling kinetics of the IPN hydrogels could be controlled by adjusting the NIPAAm/EGMA molar ratio. A faster water uptake rate and a slower water loss rate could be realized by increase the amount of EGMA in the IPN hydrogel (the shrinking rate constant was decreased from 0.01207 to 0.01195 and 0.01055 with the changing of NIPAAm/EGMA ratio from 20:0, 19.5:0.5 to 18.5:1.5). By using 2-Isopropylthioxanthone (ITX) as a photo initiator, the obtained alginate-Ca2+/P(NIPAAm-co-EGMA360) IPN hydrogels were successfully immobilized on cotton fabrics. The surface and cross section of the hydrogel were probed by scanning electron microscopy (SEM). They all exhibited a porous structure, and the pore size was increased with the amount of EGMA. Moreover, the LCST values of the fabric-grafted hydrogels were close to those of the pure IPN hydrogels. Their thermal sensitivity remained unchanged. The cotton fabrics grafted with hydrogel turned out to be much softer with the continuous increase of EGMA amount. Therefore, compared with alginate-Ca2+/PNIPAAm hydrogel, alginate-Ca2+/P(NIPAAm-co-EGMA360) hydrogel is a more promising candidate for wound dressing in the field of biomedical textile. Full article
(This article belongs to the Special Issue Smart and Functional Elastomers, Hydrogels, and Ionogels)
Figures

Graphical abstract

Review

Jump to: Research

Open AccessFeature PaperReview Internal Status of Visibly Opaque Black Rubbers Investigated by Terahertz Polarization Spectroscopy: Fundamentals and Applications
Polymers 2019, 11(1), 9; https://doi.org/10.3390/polym11010009
Received: 11 November 2018 / Revised: 14 December 2018 / Accepted: 18 December 2018 / Published: 21 December 2018
PDF Full-text (2564 KB) | HTML Full-text | XML Full-text
Abstract
We discuss the internal status of rubber composites consisting of an insulating rubber matrix and conductive carbon black (CB) fillers (“black rubber”) using polarization-sensitive terahertz time-domain spectroscopy (THz-TDS). The black rubber composites under stretched conditions exhibit a large optical anisotropy or birefringence in [...] Read more.
We discuss the internal status of rubber composites consisting of an insulating rubber matrix and conductive carbon black (CB) fillers (“black rubber”) using polarization-sensitive terahertz time-domain spectroscopy (THz-TDS). The black rubber composites under stretched conditions exhibit a large optical anisotropy or birefringence in the terahertz regime. From systematic studies, it is revealed that the large birefringence of black rubbers is due to the orientation distribution of anisotropically shaped CB aggregates in the rubber matrix and the orientation distribution is strongly linked to the mechanical deformation of the black rubber. A model simulation based on this relation between deformation and reorientation allows conversion of the birefringence (optical) information into strain (mechanical) information. In addition, the spectroscopic information obtained using the THz-TDS technique is useful to evaluate the changes in the internal conductive filler network caused by the mechanical deformation. Our findings demonstrate that the terahertz polarization spectroscopy is a promising nondestructive inspection method for contactless investigation of the internal condition of black rubber composites. Full article
(This article belongs to the Special Issue Smart and Functional Elastomers, Hydrogels, and Ionogels)
Figures

Figure 1

Polymers EISSN 2073-4360 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top