聚乙烯醇-壳聚糖复合水凝胶的溶胀性能

以聚乙烯醇(PVA)和壳聚糖为原料、以戊二醛为交联剂,在醋酸溶液中合成了聚乙烯醇-壳聚糖复合水凝胶,研究了影响水凝胶溶胀性能的多种因素,实验结果表明,该凝胶对pH、离子、温度敏感,且在pH=3.13盐酸溶液、常温下的蒸馏水及8℃蒸馏水中溶胀度较大,分别为1 112.2%、974.2%、1 036.8%,凝胶溶胀度随着干燥温度及干燥时间的增加而减小,聚乙烯醇种类对水凝胶溶胀性能有显著影响,PVA-1788与壳聚糖形成的水凝胶溶胀度最大为2 074.1%。聚乙烯醇-壳聚糖复合水凝胶因具有优良的机械强度、生物相容性及生物降解性,同时又具有pH/离子/温度敏感性,因此日益显示其在生物医学材料等领域的重要性。     

PVA/SA复合水凝胶溶胀及无机三氮离子传递性能

以聚乙烯醇（PVA）、海藻酸钠（SA）、活性炭、硼酸和氯化钙为原料,制备复合水凝胶微生物固定化载体材料,分析了离子在水凝胶膜中的扩散渗透机理,采用池膜法测定水凝胶的NH⁺₄、NO^-₂、NO^-₃离子扩散性能。结果表明,在PVA、SA、活性炭含量分别为4％、2.0%及0.2%时,以5%的氯化钙的饱和硼酸溶液为交联剂,交联时间15 min的条件下制备的固定化脱氮微生物载体传递性能最佳。复合水凝胶平衡溶胀度、扩散系数随PVA浓度升高而增大,随SA浓度升高溶胀度降低,离子扩散系数起初随SA浓度升高而升高,随后出现拐点。3种无机氮离子在水凝胶中的传递速率依次为NH⁺₄>NO^-₂>NO^-₃,遵从离子有效截面积小,传递速率大的规律。改变水凝胶制备条件、原料配比对NO^-₂、NH⁺₄的渗透系数影响较大,而对NO^-₃影响较小。     

丙烯酰胺类共聚物水凝胶的合成及性能研究

用自由基聚合法合成了不同摩尔配比的HEMA／AM共聚物水凝胶材料。研究了单体组成、温度、pH值、离子强度等因素对凝胶溶胀性能的影响。结果表明：水凝胶的溶胀速度较快;水凝胶在pH值小于4及pH值大于9的酸、碱溶液中发生水解,导致水凝胶的饱和含水量大幅增加,而在弱酸性溶液中几乎没有变化;水凝胶的饱和含水量对离子强度的变化不够敏感;随着温度的升高水凝胶的饱和含水量略有减少,说明此类水凝胶对温度的敏感性也较弱。     

高强度耐溶胀仿软骨PVA/CS复合水凝胶的合成及性能

利用冻融循环并浸泡柠檬酸钠的方法,制备了聚乙烯醇/壳聚糖（PVA/CS）复合水凝胶。通过FTIR、XRD,DSC和SEM 表征了其结构和形貌,并测试了其机械性能。结果表明：PVA单网络水凝胶网孔尺寸在1.5~8.2 μm之间,自由水含量为76.2%,有效交联密度为0.0288 mol/L,抗拉和抗压强度仅为0.2 MPa和1.4 MPa。而复合水凝胶由于氢键与离子键的协同交联作用,其网孔尺寸和自由水含量分别降低至1.5 μm和1.45%,有效交联密度提高至0.421 mol/L,抗拉和抗压强度分别为9.3 MPa和16.6 MPa。同时,该水凝胶还具有优异的抗疲劳与耐溶胀特性,连续压缩10次以后水凝胶的抗压强度和韧性分别为初始值的88.1%和84.3%,在去离子水中溶胀平衡后的抗拉强度高达4.3 MPa。     

壳聚糖/聚乙烯醇复合水凝胶制备及性能研究

成功制备了壳聚糖/聚乙烯醇(CS/PVA)复合水凝胶。考察了聚乙烯醇与壳聚糖的质量比及戊二醛用量等对水凝胶溶胀度、机械强度等的影响。结果表明:当聚乙烯醇与壳聚糖质量比为2,戊二醛浓度为0.213 mol/L时,水凝胶的综合性能最佳。     

苯乙烯乳液共聚聚丙烯酸复合凝胶制备及溶胀性能

以丙烯酸(AA)为亲水单体、苯乙烯、二乙烯苯为疏水单体,OP-10为乳化剂,在水中进行自由基共聚得到改性凝胶。测定了不同试剂原料配比下的复合结构凝胶的平衡溶胀率、溶胀速率,发现复合结构凝胶(MCG)平衡溶胀率随疏水单体用量增加和乳化剂用量减小而增加,溶胀速率随疏水单体用量增加先增加后降低,随乳化剂用量增加而加快。复合结构凝胶具有弹性体特征,避免了小分子交联剂交联的常规凝胶的脆性。     

壳聚糖水凝胶溶胀性能的研究

壳聚糖水凝胶在pH7.0,0.2%甘氨酸缓冲溶液中的最高溶胀比R为637.5,溶胀体积比Rv为12.75;当pH≤7.0时,表现强的吸水性;pH>8.5时脱水收缩;在<1%NaCl溶液中,表现出不同程度的吸胀性;在≥1%NaCl溶液中,无吸胀性,随着环境温度的升高,吸胀性下降;甲醇作为成胶介质,凝胶的吸胀性最强;交链度与壳聚糖水凝胶的Rv成反比。因此认为,壳聚糖水凝胶在农业、医药、化工和生物学的应用及研究中将表现重要作用。     

聚（N-异丙基丙烯酰胺）／海藻酸钠／粘土复合水凝胶的制备及溶胀动力学研究

以无机粘土为交联剂制备了聚（N-异丙基丙烯酰胺）／海藻酸钠／粘土（PINPA／SA／Clay）复合水凝胶,通过红外光谱、X射线衍射对凝胶的结构进行了表征,结果表明：粘土的结晶结构已被破坏,粘土规整的片层被剥离并在凝胶中无序分布,起到交联剂的作用;随粘土含量的增加,凝胶网络交联密度增加,溶胀速度下降。在不同温度下对不同粘土含量的凝胶进行了溶胀动力学测试,表明在低于其相转变温度时,凝胶的扩散类型为non－Fickian扩散。     

基于苯硼酸微凝胶复合水凝胶的制备及性能

以3-氨基苯硼酸(AAPBA)为葡萄糖敏感基元,N,N′-二甲基丙烯酰胺(DMAA)、丙烯酰胺(AAm)为单体,N,N-亚甲基双丙烯酰胺(MBA)为交联剂,十二烷基硫酸钠(SDS)为表面活性剂,过硫酸钾(KPS)为引发剂,70℃下乳液聚合制备微凝胶。以微凝胶为反应基质作为交联点,添加相应单体,制备复合水凝胶P(AAPBA-DMAA-co-AAm)/P(AAPBA-DMAA-co-AAm)。通过FTIR、SEM和TGA分别对复合水凝胶的化学结构、表面结构和热稳定性能进行表征。通过称量法测试复合水凝胶对葡萄糖的响应性,得出添加微凝胶提高了水凝胶的响应速率,平衡时间在50 min左右。多次的重复实验说明微凝胶的添加提高了水凝胶的机械强度,复合水凝胶的重现性良好。复合水凝胶对葡萄糖响应性能优异,为凝胶用于药物释放体系奠定了基础。     

丙烯酸十八酯与甲基丙烯酸共聚物凝胶的合成及其性能

以无水乙醇为溶剂,N,N’-亚甲基双丙烯酰胺(MBAA)为交联剂,在50℃下将丙烯酸十八酯(ODA)与甲基丙烯酸(MAA)进行共聚,合成了丙烯酸十八酯(ODA)与甲基丙烯酸(MAA)的共聚物凝胶：研究了共聚组成对凝胶性能的影响。结果表明：经二甲亚砜(DMSO)平衡溶胀后的凝胶,在[ODA]：[MAA]摩尔比为1：3时,具有较高的规整性和较高的溶胀倍率。DSC测定表明在温度交化过程中聚合物凝胶存在有序．无序结构的转交。将共聚物凝胶在由不同极性的溶剂环己醇和DMSO组成的混合溶剂中溶胀,发现聚合物凝胶在极性溶剂DMSO中的规整性最高,随着小极性溶剂环己醇的比例加大,混合溶剂的极性下降,聚合物凝胶在混合溶剂中的规整性逐渐降低,相交温度向低温迁移,吸热和放热量降低,至环己醇含量≥40％后,在升温-降温过程中其吸放热量均为0,不发生相交,这说明溶剂的极性对聚合物凝胶的规整性有较大的影响。     

Syntheses,characterization, and antibacterial activity of chitosan grafted hydrogels and associated mica‐containing nanocomposite hydrogels

Chitosan (CS) grafted poly[(acrylic acid)‐co‐(2‐hydroxyethyl methacrylate)] (CS‐g‐poly(AA‐co‐HEMA)) at different molar ratios of AA and HEMA, and the associated nanocomposite hydrogels of CS‐g‐poly(AA‐co‐HEMA)/mica were synthesized by radical copolymerization. The grafting positions at the amino or hydroxyl groups in the CS were identified by Fourier transform infrared spectroscopy. CS‐g‐poly(AA‐co‐HEMA) hydrogels were intercalated in the mica and the amount of hydrogel insertion did not affect the spacing of the silicate layers in mica. The higher mica loadings produced a rougher surface of the nanocomposite hydrogel. The water absorbency of the CS‐g‐poly(AA‐co‐HEMA)/mica nanocomposite hydrogels decreased with increasing levels of mica loading to a lower level than those of the CS‐g‐poly(AA‐co‐HEMA) hydrogels. Both CS‐g‐poly(AA) and CS‐g‐poly(AA‐co‐HEMA)/mica nanocomposite hydrogels exhibited a higher antiproliferative activity against Staphylococcus aureus than did the neat CS hydrogel with CS‐g‐poly(AA) revealing a very pronounced minimum inhibition concentration (MIC) of 1.56 mg mL^?1. The extent of mica loading in the CS‐g‐poly(AA‐co‐HEMA) nanocomposite hydrogels did not affect the MIC (12.5 mg mL^?1). © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Swelling behavior of polyelectrolyte complex hydrogels composed of chitosan and hyaluronic acid

Polyelectrolyte complex (PEC) hydrogels composed of various weight ratios of chitosan and hyaluronic acid were prepared. The PEC hydrogels were formed by the reaction of the oppositely charged chitosan polymers. The PEC films swelled in water rapidly, reaching equilibrium within 30 min, and exhibited relatively high swelling ratios, 243–322%, at 25°C. The swelling ratio increased with increasing temperature. The transport phenomena of all PEC samples were non‐Fickian and diffusion and relaxation controlled. The diffusion coefficients of the PEC films ranged from 2.22 × 10^?6 to 10.05 × 10^?6 cm²/s. The activation energy of the polyelectrolyte complexes ranged from 37.14 to 54.58 kJ/mol and proved to be hydrophilic. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1097–1101, 2004     

NVP接枝壳聚糖水凝胶的合成与溶胀性能

合成了N-乙烯基吡咯烷酮（NVP）接枝壳聚糖（CHI）水凝胶,讨论了NVP/CHI、引发剂、交联剂、聚合温度、乙酸浓度等因素对接枝率及凝胶溶胀性能的影响,NVP∶CHI为6时,接枝率达到300%以上. 溶胀温度、pH值、盐浓度等对凝胶溶胀性能的影响实验表明,凝胶表现出温度敏感性,在40 ℃出现最大平衡溶胀率,并观察到一级相转变;在中性或弱酸性介质中溶胀性能较好;与PVP凝胶相比,NVP接枝CHI凝胶表现出反聚电解质效应. 溶胀动力学研究表明,在溶胀前期,CHI含量较高时,凝胶趋向于非Fick溶胀,说明除了溶剂扩散外,凝胶网络链段弛豫、水分子与凝胶网络间及凝胶高分子链段间相互作用对凝胶溶胀性能的影响至关重要;CHI含量较高时则趋向于Fick溶胀.     

Synthesis and characteristics of semi‐interpenetrating polymer network hydrogels based on chitosan and poly(hydroxy ethyl methacrylate)

Semi‐interpenetrating polymer networks (semi‐IPNs), composed of chitosan and poly(hydroxy ethyl methacrylate) hydrogels, were prepared and the effects of various pH, temperatures, and an electric‐field on the swollen hydrogels were investigated. The swelling kinetics increased rapidly, reaching equilibrium within 60 min. Semi‐IPN hydrogels exhibited relatively high swelling ratios, 150～350%. The swelling ratio increased when the pH of the buffer was below pH 7 as a result of the dissociation of ionic bonds. Semi‐IPN hydrogels showed electroresponsiveness by shrinking when an electric field was applied. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 86–92, 2005     

Semi‐IPN carrageenan‐based nanocomposite hydrogels: Synthesis and swelling behavior

Inclusion of nano‐clays into hydrogels is an efficient approach to produce nanocomposite hydrogels. The introduction of nano‐clay into hydrogels causes an increase in water absorbency. In the present work, Nanocomposite hydrogels based on kappa‐carrageenan were synthesized using sodium montmorillonite as nano‐clay. Acrylamide and methylenebisacrylamide were used as monomer and crosslinker, respectively. The structure of nanocomposite hydrogels was investigated by XRD and SEM techniques. Swelling behavior of nanocomposite hydrogels was studied by varying clay and carrageenan contents as well as methylenebisacrylamide concentration. An optimum swelling capacity was achieved at 12% of sodium montmorilonite. The swollen nanocomposite hydrogels were used to study water retention capacity (WRC) under heating. The results revealed an increase in WRC due to inclusion of sodium montmorilonite clay. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Novel approach to highly porous superabsorbent hydrogels: synergistic effect of porogens on porosity and swelling rate

A novel practical strategy for preparing highly porous superabsorbent hydrogels (HPSHs) was invented. HPSHs were quantitatively prepared through an optimized rapid convenient solution polymerization of partially neutralized acrylic acid in the presence of a crosslinking agent under normal atmospheric conditions. Acetone and sodium bicarbonate were used as porosity generators (porogens) during the polymerization process to create highly porous structures. Time and sequence of addition of the porogens, as well as the gelation time of the polymerization, were recognized to affect the efficiency of the porogens. Sodium bicarbonate produced the more porous hydrogels with a higher rate of swelling. In comparison with a hydrogel prepared under porogen‐free conditions (control), acetone and sodium bicarbonate enhanced the swelling rate as high as 43–55% and 111–131% of the control, respectively. When both the porogens were used consecutively in the process, a remarkable synergistic effect was observed in the swelling rate of the products. Nearly all the two‐porogen processes resulted in foamy products from the polymerization system. With the single‐porogen systems, however, the foam formation stage was observed only in a part of the total process time. The apparent volume of the as‐synthesized foamy products prepared from the two‐porogen system was more than that of the single‐porogen systems by up to fourfolds. Morphological studies using scanning electron microscopy (SEM) showed that the two‐porogen systems created highly porous structures. The density of all the HPSHs synthesized was about 1.5 g cm^?3 and no distinct differences were observed in their equilibrium swelling. These superabsorbent hydrogels exhibited a very high rate of swelling, so that their swelling time was measured to be less than one minute. Copyright © 2003 Society of Chemical Industry     

N-异丙基丙烯酰胺凝胶在NaCl水溶液中溶胀行为的预测研究

In this paper,a model is presented to correlate and predict the swelling behavior of hydrogels in aqueous solutions of electrolytes.The model is a combination of VERS-model,"phantom network" theory and "free-volume"contribution.The VERS-model is used to calculate Gibbs excess energy; "phantom network" theory to describe the elastic properties of polymer network,and "free-volume" contribution to account for additional difference in the size of the species.To test the model,a series of N-isopropylacrylamide based hydrogels are synthesized by free radical polymerization in oxygen-free,deionized water at 25°C under nitrogen atmosphere.Then,the degree of swelling of all investigated gels as well as the partition of the solute between the gel phase and the surrounding coexisting liquid phase are measured in aqueous solution of sodium chloride.The model test demonstrates that the swelling behavior correlated and predicted by the model agrees with the experimental data within the experimental uncertainty.The phase transition appeared in the experiment,and the influences of the total mass fraction of polymerizable materials ξgel as well as the mole fraction of the crosslinking agent yCR on the swelling behavior of IPAAm-gels can also be predicted correctly.All these show the potential of such model for correlation and prediction of the swelling behavior of hydrogels in aqueous solutions of electrolytes.     

微波辐照合成聚丙烯酸水凝胶及其性能研究

采用微波辐照法合成了聚丙烯酸水凝胶,并对其溶胀性能进行了研究。所制得的凝胶不仅具有pH敏感性和良好的pH反复性,而且在pH<4的酸性溶液中表现出温度敏感性,其溶胀比随温度的升高而上升。     

pH‐thermoreversible hydrogels. I. Synthesis and swelling behaviors of the (N‐isopropylacrylamide‐co‐acrylamide‐co‐2‐hydroxyethyl methacrylate) copolymeric hydrogels

A series of pH‐thermoreversible hydrogels that exhibited volume phase transition was synthesized by various molar ratios of N‐isopropylacrylamide (NIPAAm), acrylamide (AAm), and 2‐hydroxyethyl methacrylate (HEMA). The influence of environmental conditions such as temperature and pH value on the swelling behavior of these copolymeric gels was investigated. Results showed that the hydrogels exhibited different equilibrium swelling ratios in different pH solutions. Amide groups could be hydrolyzed to form negatively charged carboxylate ion groups in their hydrophilic polymeric network in response to an external pH variation. The pH sensitivities of these gels also depended on the AAm content in the copolymeric gels; thus the greater the AAm content, the higher the pH sensitivity. These hydrogels, based on a temperature‐sensitive hydrogel, demonstrated a significant change of equilibrium swelling in aqueous media between a highly solvated, swollen gel state and a dehydrated network response to small variations of temperature. pH‐thermoreversible hydrogels were used for a study of the release of a model drug, caffeine, with changes in temperature. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 221–231, 1999