PVP/(AA-co-AMPS)互穿网络水凝胶的制备及其电场响应性研究

通过两步溶液聚合的方法制备了由丙烯酸单体（AA）与2-丙烯酰胺-2-甲基丙磺酸（AMPS）的共聚物和聚乙烯基吡咯烷酮（PVP）形成的具有互穿网络状结构（IPN）的新型聚合物水凝胶。并研究了共聚单体配比、PVP和交联剂对水凝胶电场响应性及力学性能的影响。探索了凝胶在电场作用下的弯曲机理。实验结果表明：此种具有IPN结构的凝胶具有较好的电场响应性和力学强度。当n（AA）：n（AMPS）达到7：3,ω（PVP）=16％,ω,（交联剂）=0．05％时,水凝胶的综合性能达到最好。     

PAAm／PEG／PVP半互穿网络水凝胶的制备、表征及茶碱释放研究．

以N,N-亚甲基双丙烯酰胺（N,N-MBA）为交联剂、过硫酸钾（KPS）为引发剂·通过丙烯酰胺（AAm）、聚乙二醇（PEG）和聚乙烯吡咯烷酮（PVP）发生共聚反应制备具有半互穿网络结构的水凝胶PAAm／PEG／PVP。采用红外光谱（FTIR）、热重分析（TG）对水凝胶的结构和热学性质进行了分析,研究了中性条件下水凝胶的溶胀性能,并进一步研究了其负栽茶碱在不同缓冲溶液中的释放行为。     

壳聚糖/聚醚半互穿网络水凝胶的性能

以壳聚糖和聚醚为原料,戊二醛为交联剂,在醋酸溶液中制备了壳聚糖/聚醚水凝胶,反应温度45℃,聚醚和壳聚糖的质量比为0.4,戊二醛浓度为0.053 mol/L,壳聚糖黏均相对分子质量为24.86×104时,其凝胶饱和溶胀度为876.25%;反应温度45℃,聚醚和壳聚糖的质量比为0.6,戊二醛浓度为0.267 mol/L,壳聚糖黏均相对分子质量为24.86×104时,其凝胶硬度为151.896 kPa。     

温度及pH敏感性互穿网络水凝胶的制备研究

采用分步法制备了聚丙烯酸/N-异丙基丙烯酰胺互穿网络水凝胶,研究了互穿网络水凝胶的溶胀性能。结果表明,当水溶液的pH增大时,水凝胶的溶胀率显著增加。在一定的温度范围内,水凝胶的溶胀率随温度升高而减小。聚丙烯酸/N-异丙基丙烯酰胺互穿网络水凝胶表现出显著的温度及pH敏感双重特性。     

具有pH及温度敏感性的互穿网络水凝胶的合成及其性能研究

用自由基聚合合成了具有两亲性的N-异丙基丙烯酰胺(NIPAm)与衣康酸(IA)共聚物水凝胶(NIPAm-co-IA),利用互穿网络(IPN)技术合成了壳聚糖(CS)异丙基丙烯酰胺与衣康酸互穿网络水凝胶IPN(CS/NIPAm-co-IA).研究表明, IPN(CS/NIPAm-co-IA)水凝胶具有良好的pH及温度敏感性,研究了其对辅酶A的控制释放,发现其对辅酶A具有良好的控制释放作用.     

预辐照聚乙烯薄膜接枝丙烯酸/丙烯酰胺制备水凝胶互穿网络的研究

通过二次接枝方法，在预辐射聚乙烯(PE)薄膜上分别接枝丙烯酸(AAc)和丙烯酰胺(AAm)制得了具有pH敏感性和温度敏感性水凝胶互穿网络(IPN)。研究了不同辐照源、单体浓度、阻聚剂的浓度等对接枝率的影响，经测定，所得到的PE-g-Amn／AAc水凝胶膜具有明显的pH敏感性。     

蓖麻油聚氨酯半互穿网络聚合物的合成与性能研究

以甲苯二异氰酸酯分别与甲基丙烯酸羟乙酯和丙烯酸羟丙酯及蓖麻油作用合成了两种预聚体;然后再分别与甲基丙烯酸羟乙酯、甲基丙烯酸羟丙酯、丙烯酸羟乙酯、丙烯酸羟丙酯及苯乙烯5种单体混合.在紫外光照射下形成半互穿网络聚合物样品。分析结果表明.第一种预聚体的系列样品拉伸强度高.伸长率低;而第二种预聚体的系列样品则伸长率较高.拉伸强度较低。另外,这两种预聚体和苯乙烯单体形成的样品综合性能都比其他样品要好。     

聚(N-异丙基丙烯酰胺)/聚丙烯酸半互穿网络微凝胶的合成及表征

利用IPN技术合成了一种具有温度和pH双重敏感性的聚（N-异丙基丙烯酰胺）/聚丙烯酸半互穿网络微凝胶（PNIPAM/PAAc semi-IPN）。这种微凝胶在酸性条件下发生典型的体积相转变;而在弱碱性条件下,当温度低于聚（N-异丙基丙烯酰胺）（PNIPAM）微凝胶的体积相转变温度（VPTT）时,微凝胶的粒径随着温度的上升而增大,当温度达到VPTT后,粒径突然急剧减小,并随着温度的逐渐上升而减小,最终趋向平衡。     

聚丙烯酸/聚乙烯醇互穿网络水凝胶制备及其对结晶紫的控制释放性能的研究

以过硫酸铵为引发剂,采用溶液聚合和连续的互穿网络技术,制备了一系列聚丙烯酸(PAA)/聚乙烯醇(PVA)互穿网络水凝胶。测量了水凝胶在不同pH缓冲溶液中的溶胀性能。以结晶紫为模板药物,考察了在不同的pH缓冲溶液中的PAA/PVA互穿网络水凝胶控释作用。结果表明,药物的释放量可以通过改变体系的pH值加以调控。     

PAA/PNIPAAm互穿网络水凝胶的微波合成与性能研究

以微波为辐射源,对丙烯酸(AA)水溶液进行辐照制得了PAA水凝胶。将脱水后的PAA水凝胶浸泡于含引发剂过硫酸钾(K_2S_2O_8)和交联剂N,N’-亚甲基双丙烯酰胺(BIS)的N-异丙基丙烯酰胺(NIPAAm)水溶液中,待溶胀平衡后取出,进行第二次微波辐照反应,制备了聚丙烯酸/聚N-异丙基丙烯酰胺互穿聚合物网络(PAA/PNIPAAm IPN)水凝胶,并对其溶胀性能进行了研究。研究结果表明,合成的IPN水凝胶兼具pH敏感性和温度敏感性,有望在药物控制释放领域得到应用。     

pH敏感聚合物水凝胶的实验研究

合成(聚丙烯酸)—CO—(α—甲基丙烯酸)水凝胶,具有很好的pH敏感性和一定的温度敏感性。这种水凝胶在碱性条件下的溶胀率远大于酸性条件下的溶胀率。在合成凝胶时,交联剂浓度和单体浓度都会影响聚合物反应的速度和性能,直接影响凝胶的结构,从而影响凝胶的性能,而且溶液中的离子浓度对凝胶的溶胀率也造成影响,其它条件相同,离子浓度越大,溶胀率越小。本文也研究了此凝胶的可逆性。在通过大量的实验后,结果表明：丙烯酸和α—甲基丙烯酸单体的摩尔比为1：0．75,在60℃合成的凝胶有较好的性能。     

pH响应PAAm-g-PEG/PVP半互穿网络水凝胶的制备以及溶胀动力学

采用硝酸铈胺-聚乙二醇为氧化-还原引发体系,N,N-亚甲基双丙烯酰(N,N-MBA)为交联剂,通过简单的自由基聚合法,设计合成了一种聚(丙烯酰胺-g-聚乙二醇)/聚乙烯吡咯烷酮PAAm-g-PEG/PVP接枝交联结构的半互穿网络水凝胶。研究了它们在不同pH值缓冲溶液中的溶胀与扩散行为以及溶胀动力学;并采用红外光谱和热分析系统对其结构和热性能进行了分析测量。实验结果表明:水凝胶的溶胀行为和扩散模式取决于溶液的pH值。随着缓冲溶液pH值增加,平衡溶胀率减小;在不同的缓冲溶液中理论最大吸水量S∞与实验值基本相一致。水凝胶的溶胀行为可以通过选择加入不同分子量大小的PEG来调节和控制。     

Swelling behaviors of ionic poly(N,N‐dimethylacrylamide‐co‐acrylamide) hydrogels in various media

Polyelectrolyte hydrogels were synthesized from N,N‐dimethylacrylamide, acrylamide, and itaconic acid with ammonium persulfate as a free‐radical initiator in the presence of methylene(bis)acrylamide as a crosslinker. The swelling behavior of the ionic poly(N,N‐dimethylacrylamide‐co‐acrylamide) hydrogels was investigated in pure water, in KSCN solutions with pHs 4 and 9, and in water–acetone mixtures according to the itaconic acid content in the hydrogel. The pulsatile swelling behavior of these hydrogels was studied both in water–acetone and in pH 2–9 buffer solutions. Although the equilibrium swelling ratio of the hydrogels with low concentrations of itaconic acid was almost not affected by changes in the temperature, the equilibrium swelling ratio of the hydrogels with high concentrations of itaconic acid increased in the temperature range of 20–50°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2140–2145, 2007     

Water and synthetic urine sorption capacity of cellulose‐based hydrogels under a compressive stress field

A new apparatus was developed and used to investigate the swelling behavior of crosslinked hydrophilic polymers under an applied load as a function of the absorbed weight in both water and water solutions. A model able to predict the material water uptake as a function of the isotropic compressive stress was also studied. Centrifugation tests were performed to measure the material retention capacity under load, in both water and synthetic urine. The polymers studied in the tests were from a particular class of superabsorbent hydrogels based on cellulose derivatives chemically crosslinked with divinyl sulfone. The hydrogels showed high sorption and retention capacity in both water and water solutions, both in the free state and under load, and significant variations were observed during the modulation of the dry sample porosity.© 2004 Wiley Periodicals, Inc.J Appl Polym Sci 91: 3791–3796, 2004     

Stiffness xanthan hydrogels: synthesis,swelling characteristics and controlled release properties

Summary  New xanthan hydrogels were synthesized at 90 C in water acid media using adipic acid dihydrazide (ADH) as crosslinking agent, in the presence of 1-ethyl-3[3-dimethyl amino] propyl carbodiimide hydrochloride (EDCI) as reagent. In these conditions, xanthan chains are in a predominantly helical conformation and through rheological measurements the influence of the temperature over the helix-coil transition was assessed. Xanthan hydrogels with different concentration in polysaccharide and ADH were obtained and characterised by elemental analysis and swelling properties. High concentration of xanthan (i.e. 25gL^-1) is needed to obtain gel due to the low available carboxylic functions in the helical conformation. During the swelling analysis, it was noted that high temperature (i.e. 90 C) favoured the conformational transitions within the network. The drug loading and releasing properties were estimated using methylene blue as model molecule and different experimental pH and ionic strength conditions.     

Characterization of hydrogels based on chitosan and copolymer of poly(dimethylsiloxane) and poly(vinyl alcohol)

Copolymers composed of poly(vinyl alcohol) (PVA) and poly(dimethylsiloxane) (PDMS) were crosslinked with chitosan to prepare semi‐interpenetrating polymer network (IPN) hydrogels by an ultraviolet (UV) irradiation method for application as potential biomedical materials. PVA/PDMS copolymer and chitosan was cast to prepare hydrogel films, followed by a subsequent crosslinking with 2,2‐dimethoxy‐2‐phenylacetophenone as a nontoxic photoinitiator by UV irradiation. Various semi‐interpenetrating polymer networks (semi‐IPNs) were prepared from different weight ratios of chitosan and the copolymer of PVA/PDMS. Photocrosslinked hydrogels exhibited an equilibrium water content (EWC) in the range of 65–95%. Swelling behaviors of these hydrogels were studied by immersion of the gels in various buffer solutions. Particularly, the PCN13 as the highest chitosan weight ratio in semi‐IPN hydrogels showed the highest EWC in time‐dependent and pH‐dependent swelling. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2591–2596, 2002     

Thermoreversible hydrogels X: Synthesis and swelling behavior of the (N‐isopropylacrylamide‐co‐sodium 2‐acrylamido‐2‐methylpropyl sulfonate) copolymeric hydrogels

A series of thermosensitive hydrogels were prepared from various molar ratios of N‐isopropylacrylamide (NIPAAm) and sodium‐2‐acrylamido‐2‐methylpropyl sulfonate (NaAMPS). Factors such as temperature and initial total monomer concentration and different pH solutions were investigated. Results indicated that the more the NaAMPS content in hydrogel system, the higher the swelling ratio and the gel transition temperature; the higher the initial monomer concentration, the lower the swelling ratio. The result also indicated that the NIPAAm/NaAMPS copolymeric hydrogels had different swelling ratios in various pH environments. The present gels showed a pH‐reversible property between pH 3 and pH 10 and thermoreversibility. The swelling ratios of copolymeric gels were lower in a strong alkaline environment because the gels were screened by counterions. Finally, the drug release behavior of these gels was also investigated in this article. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1760–1768, 2000     

Water absorption and mechanical properties of electrospun structured hydrogels

Electrospun nanofibers are made when electrostatic forces overcome the surface tension of a polymer solution, causing an electrically charged jet to be ejected; as the jet travels through the air, the solvent evaporates, leaving behind an electrically charged fiber, which can be collected in the form of a nonwoven sheet. A superabsorbent was added to a polymer solution containing an elastomer (concentrations = 0–85%). The mixture was electrospun, producing nanofibers in which the superabsorbent particles were held in place with nanoscale elastic fibers. The nanofibers were tested for absorbency in water and synthetic urine. Fluid absorption by the nanofibers led to the formation of structured hydrogels. Increases in the weight gain from water absorption ranged from 400 to 5000%. The linear dimensions of samples cut from the nonwoven sheet were measured; wetting the superabsorbent increased the thickness dimension of the sheet dramatically and produced a smaller change in the plane of the sheet. The rate of water absorption was calculated; the samples containing 0–70% superabsorbent reached essentially their maximum absorbency within 5 s. The excellent strength and elasticity of the wet samples make these structured hydrogels ideal for many uses, including wound care, drug delivery, and sanitary goods. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 427–434, 2005     

新型胶原基pH敏感水凝胶的制备及性能

在紫外光辐照下,以H2O2为引发剂,采用接枝共聚法制备胶原/聚乙烯吡咯烷酮/丙烯酰胺（Collagen/PVP/AM）pH敏感水凝胶。考察了原料配比和干燥方法对凝胶溶胀性能的影响,研究了其pH敏感性及pH溶胀-退胀特性。制备的水凝胶具有较快的溶胀速率,在5 min时的吸水率可达94％左右。所制备的水凝胶有明显的pH敏感性且pH溶胀-退胀的可逆性良好。傅里叶变换红外光谱法（FTIR）和示差扫描量热法（DSC）结果表明,在保持胶原三股螺旋结构的同时,材料间发生了化学交联,材料的热稳定性显著提高,从而扩大了材料的应用范围。     

Electric stimuli responses to poly(vinyl alcohol)/chitosan interpenetrating polymer network hydrogel in NaCl solutions

An interpenetrating polymer network (IPN) hydrogel composed of poly(vinyl alcohol) (PVA) and chitosan exhibited electric‐sensitive behavior. The PVA/chitosan IPN hydrogel was synthesized by an ultraviolet (UV) irradiation method that is used in several biomedical and industrial fields. The swelling behavior of the PVA/chitosan IPN hydrogel was studied by immersion of the gel in NaCl aqueous solutions at various concentrations. The swelling ratio decreased with increasing concentration of NaCl solution. The stimuli response of the IPN hydrogel in electric fields was also investigated. When a swollen PVA/chitosan IPN was placed between a pair of electrodes, the IPN exhibited bending behavior in response to the applied electric field. The bending angle and the bending speed of the PVA/chitosan IPN increased with increasing applied voltage and concentration of NaCl aqueous solution. The PVA/chitosan IPN also showed stepwise bending behavior depending on the electric stimulus. In addition, thermal properties of PVA/chitosan IPN were investigated by differential scanning calorimetry (DSC) and dielectric analysis (DEA). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2285–2289, 2002