Swelling kinetics and release characteristic of crosslinked chitosan: Polyether polymer network (semi-IPN) hydrogels

The aqueous swelling kinetics of a series of crosslinked chitosan (cr-CS) with glutaraldehyde (GA) interpenetrating polyether hydrogels have been studied as functions of pH, the N-deacetylation degree of chitosan, the amount of crosslinking agent, the electrolyte composition in solution, temperature, and gel composition. Based on these results, the swelling mechanism of the hydrogels was discussed. The release profiles of chlorhexidini acetas from the semi-IPN were also investigated. © 1994 John Wiley & Sons, Inc.     

Synthesis and degradation of intelligent hydrogels containing polyacetal segments

Intelligent hydrogels were first obtained by copolymerization of telechelic poly(1,3-dioxolane) (pDXL) with acrylic acid, acrylamide, N-isopropylacrylamide respectively. The synthesis and characterization of the networks were discussed. The swelling behavior of the hydrogel was dependent on the solubility parameter of the solvents and hydrogels. The networks containing polyacetal segments (pDXL) can degrade by acid in different solvents. DXL and few other cycle molecules measured by GC-MS analysis were formed after degradation. According to the degradation products, the polymerization mechanism can be testified.     

Viscoelasticity,mechanical properties,and in vivo biocompatibility of injectable polyvinyl alcohol/bioactive glass composite hydrogels as potential bone tissue scaffolds

Abstract

An injectable composite hydrogel composed of polyvinyl alcohol (PVA) and bioactive glass (BG) particles were synthesized by a physical crosslinking approach. The morphology, mechanical properties, and viscoelasticity of the PVA/BG composite hydrogel were characterized. Scanning electronic microscopy (SEM) showed uniform and homogeneous distribution of BG particles throughout the composite hydrogel. The incorporation of 2.5?wt% of BG particles in the composite hydrogel formulations, enhanced the static compressive strength and static elastic modulus by 325% and 150%, respectively. The storage molds (G′) was greater than the loss modules (G′′) at all the frequency range studied, which revealed a self-standing elastic composite hydrogel with a smooth injectability. The PVA/BG composite hydrogel was also implanted subcutaneously in the dorsal region of adult male rats. After 4?weeks of implantation, no inflammatory cells were seen within and around the implant, which indicated that the composite hydrogel was biocompatible. The properties of the synthesized injectable PVA/BG composite hydrogel demonstrate its capability toward bone regeneration.     

酶生物燃料电池

综述了酶生物燃料电池的研究进展，特别是近年来在电池结构、性能以及电池的正极和负极研究等方面的成果。详细介绍了酶燃料电池中酶电极的制备方法和用于酶电极修饰材料的研究现状，对酶燃料电池研究中需要解决的问题和发展方向进行了探讨。     

Microwave-assisted Preparation of Temperature Sensitive Poly（N-isopropylacrylamide） Hydrogel with Improved Responsive Properties

Poly(N-isopropylacrylamide) (PNIPAM) hydrogel, which is insoluble but shrinkable or swellable in aqueous media when temperature rises or drops across 33oC1,2, has been extensively studied due to its potential applications in the fields of controlled drug …     

智能性水凝胶

“智能”材料具有传感、处理和执行功能，水凝胶作为智能材料其应用前景良好。本文综述了智能水凝胶的近期研究发展，以Ｆｌｏｒｙ的溶胀理论着重探讨了刺激响应性，并介绍了化学机械现象及凝胶相转变。     

高强度聚乙烯醇/聚苯胺/聚吡咯/TiO2导电杂化水凝胶的制备与性能

本文以聚乙烯醇(PVA)、苯胺(ANI)、吡咯(Py)及钛酸丁酯(TBOT)为原料,通过溶胶-凝胶法、原位氧化聚合法及冷冻-融溶法一步得到聚乙烯醇/聚苯胺/聚吡咯/TiO 2(PVA/PANI/PPy/TiO 2)杂化水凝胶。结果表明,该杂化水凝胶具有优异的力学性能和导电性能。当n(ANI)∶[KG-*3/5]n(Py)=8∶[KG-*3/5]2(TBOT体积为100μL)时,其压缩强度高达2.45 MPa。同时,在外加电源的作用下,该凝胶能够使灯泡发光。当n(ANI)∶[KG-*3/5]n(Py)=2∶[KG-*3/5]8(TBOT体积为150μL)时,杂化水凝胶的电导率(0.25 S/m)最好。该杂化水凝胶有望广泛地应用在柔性可穿戴电子器件、安全离子电池、传感器和生物器件等领域。     

智能型水凝胶

智能型水凝胶是一类具有广泛应用前景的功能高分子材料，但由于传统水凝胶存在一些缺点因而限制了其应用，因此近年来围绕提高传统水凝胶的性能做了大量研究工作。本文从四个主要方面综述了近年来智能型水凝胶改性的研究进展。     

Positron annihilation studies of poly(N‐isopropyl acrylamide) gel in mixed solvents

Positron annihilation lifetime spectroscopy was used to characterize the reentrant volume‐phase‐transition behavior of poly(N‐isopropyl acrylamide) hydrogel in an ethanol/water mixed solvent. The polymer gel was synthesized with γ irradiation. The ortho‐positronium lifetime (τ₃) in the gel slowly increased with an increase in the ethanol content in the mixed solvent. τ₃ was not influenced by the volume phase transition. The ortho‐positronium intensity decreased with the collapse of the gel in an approximately 10% ethanol/water mixture. When swelled in pure ethanol, τ₃ initially increased with the solvent amount in the gel, showing the destruction of intramolecular hydrogen bonding and the relaxation of polymer chains. The lower critical solution temperature of the gel in the 10% ethanol/water mixture was lower than that in pure water, and τ₃ for various solvent contents showed behavior similar to that seen in pure solvent. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1028–1036, 2002     

Studies on the Synthesis and Properties of Temperature Responsive and Biodegradable Hydrogels

Novel linear poly(NIPA‐co‐CL) copolymers have been synthesized by radical copolymerization of N‐isopropylacrylamide (NIPA) and 2‐methylene‐1,3‐dioxepane (MDO). The structure of copolymers was confirmed by ¹H NMR and IR spectroscopy. Cross‐linked poly(NIPA‐co‐CL) hydrogels have also been prepared in toluene using N,N′‐methylenebisacrylamide as cross‐linking agent. The hydrogels thus obtained exhibit good temperature response and are biodegradable in the presence of proteinase K.

Temperature influence on the enzymatic degradation by proteinase K of poly(NIPA‐co‐CL) hydrogel (G‐60).