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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。 相似文献
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壳聚糖水凝胶溶胀性能的研究 总被引:2,自引:0,他引:2
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。 相似文献
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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。 相似文献
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丙烯酰胺/丙烯酸水凝胶的pH敏感性研究 总被引:3,自引:0,他引:3
测定并研究了丙烯酰胺/丙烯酸凝胶的pH敏感性,及各因素对其性能的影响,实验表明:当丙烯酰胺/丙烯酸比在2:3附近时,形成的凝胶溶胀比最大;随着交联剂含量的增加,会使凝胶的溶胀比显著减小;引发剂含量适当时,可使凝胶溶胀比达到最大。并且从离子强度、相互反应方面对这种变化进行了解释。 相似文献
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pH敏感高分子水凝胶的合成及性能研究 总被引:1,自引:0,他引:1
从分子设计的角度出发,选用具有优良pH敏感的丙烯酸(AAc)为基本原料,制备了pH敏感水凝胶,系统研究了水凝胶的基本物理性能(密度、平均分子量、交联密度、平衡态水含量、固定电荷密度等),测试了水凝胶在不同离子强度下的溶胀、退溶胀性能,并对其响应机理进行了探讨,同时对水凝胶的机械性能进行测试.结果表明:pH敏感水凝胶的机械性能随着pH值增大而变化,其变化幅度最大可达到80%;其机械性能强烈依赖于平衡态溶胀率;离子强度的大小也对水凝胶的机械性能有着决定性影响. 相似文献
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温度和pH值对智能水凝胶溶胀行为的影响 总被引:1,自引:0,他引:1
以N-马来酰化壳聚糖(N-MACH)为交联剂,N-异丙基丙烯酰胺(NIPAAm)为单体,羧甲基纤维素钠(CMC)为半互穿材料,分别合成了PNIPAAm和PNIPAAm/CMC半互穿网络智能水凝胶,研究了两种水凝胶在不同温度的去离子水和不同pH值的缓冲溶液中的溶胀现象,结果表明介质温度和pH值对水凝胶的溶胀行为有显著影响。在温度和pH值一定时,水凝胶的溶胀率随着交联剂用量的增加而下降,随着CMC用量的增加而上升。 相似文献
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《国际聚合物材料杂志》2012,61(7):513-536
ABSTRACT Chemically crosslinked poly(acrylamide-co-maleic acid) [poly(AAm-co-MA)] hydrogels were prepared by simultaneous free radical copolymerization of acrylamide (AAm) with maleic acid (MA) in presence of di or tri functional crosslinking agents using ammonium persulfate-N,N,N′,N′-tetramethylethylenediamine (APS-TMEDA) redox-initiating system. The poly(AAm-co-MA) hydrogels formation was confirmed by IR studies. The influence of crosslinkers such as N,N′-methylene-bis-acrylamide (MBA) and 2,4,6-triallyloxy-1,3,5-triazine (TATA) on swelling/de-swelling characteristics were studied in detail for poly(AAm-co-MA) hydrogels containing different amounts of maleic acid. The present investigation also deals with the influence of concentration of crosslinker and initiator on the swelling behavior of poly(AAM-co-MA) hydrogels. The effect of various salts on swelling capacity was studied. In addition, the effect of simulated biological fluids and pH solutions on the swelling of hydrogels was also studied in detail. 相似文献
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《国际聚合物材料杂志》2012,61(11):867-892
Crosslinked hydrogels comprising acrylamide (AAm) and maleic acid (MA) were synthesized by free radical polymerization in presence of a crosslinker using ammonium persulfate (APS) and N,N,N1,N1-tetramethylethylenediamine (TMEDA) as initiator and activator, respectively. The crosslinked hydrogel formation was confirmed by IR analysis. The swelling/de-swelling characteristics were studied in detail for crosslinked poly(acrylamide-co-maleic acid) [poly(AAM-co-MA)] hydrogels containing different amounts of maleic acid. Four different crosslinkers such as 1,2-ethyleneglycol dimethacrylate (EGDMA), 1,4-butanediol diacrylate (BDDA), 1,6-hexanediol diacrylate (HDDA), and diallyl phthalate (DP) were utilized to study their influence on the swelling behavior of the hydrogels. The effect of reaction parameters such as the concentration of crosslinker and initiator on swelling capacity of the crosslinked poly(AAm-co-MA) hydrogels was also investigated. Further, the influence of various salts, simulated biological fluids, and pH solutions on the swelling pattern of hydrogels was studied extensively. Phase separation morphology of crosslinked hydrogels was also studied by differential scanning calorimetry. The morphology of crosslinked hydrogels were revealed using scanning electron microscopy (SEM). 相似文献
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高强度水凝胶P(HEMA-co-NEVER)溶胀特性的研究 总被引:1,自引:0,他引:1
该文研究了酚醛环氧型乙烯基酯树脂(NEVER)/甲基丙烯酸-β-羟乙酯(HEMA)共聚水凝胶的溶胀性质。NEVER质量分数的增大,加强了水凝胶内部疏水基团间的相互作用,使平衡含水量EWC从39.7%下降到15.9%,聚合物体积分数φ2从0.5440上升到0.8085。溶胀介质离子强度增大,极性增强,形成了更加紧密的低溶胀水凝胶,导致产生盐出效应,水凝胶初始溶胀速率r0从0.189g水·g-1干胶·h-1下降到0.047g水·g-1干胶·h-1,理论最大吸水量S∞也从0.395g水·g-1干胶降到0.364g水·g-1干胶。水凝胶溶胀初期表现为Fickian行为,扩展溶胀符合Schott二级动力学方程。当温度由278K升至323K,水凝胶样品H/N3的r0从0.060g水·g-1干胶·h-1升高到0.287g水·g-1干胶·h-1,但S∞却从0.559g水·g-1干胶降到0.351g水·g-1干胶。热力学研究表明,水凝胶在水中的溶胀过程是放热过程。 相似文献
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以N—N亚甲基双丙烯酰胺为交联剂,以过硫酸钾一亚硫酸氢钠为引发剂,甲基丙烯酸-2(甲氨基)乙酯作为主要单体,与N-乙烯基吡略烷酮和衣康酸进行自由基水溶液共聚合,通过改变单体物质的量比及交联剂用量制备一系列温敏水凝胶。对制备的水凝胶结构通过红外进行表征,研究其对温度的敏感性行为。实验证明:随N-乙烯基吡咯烷酮和衣康酸比例的增大,凝胶的温敏区间(35—38℃)趋于稳定,凝胶的吸水膨胀率不断降低,凝胶吸水膨胀率下降程度增大;单体比例一定的条件下,凝胶的吸水膨胀率随温度升高而减小;交联剂用量对凝胶的温敏区间影响不大,随交联剂用量的增加吸水膨胀率先增大后减小,当交联剂用量为4.5‰时,吸水膨胀率达到最大。 相似文献
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采用紫外辐照方法,以简单易得的丙烯酸二甲胺基乙酯(DMAEA)、正溴己烷为原料,制得丙烯酰氧乙基二甲基己基溴化铵(6CQ),其与2-羟基乙基丙烯酸酯(HEA)反应,制备了四种6CQ与HEA质量比不同的丙烯酸羟乙酯-co-丙烯酰氧乙基二甲基己基溴化铵p(HEA-co-6CQ)季铵盐型水凝胶(命名为N9010,N8020,N7030,N6040)。通过FTIR与1HNMR确证了产物结构。考察了温度、时间及电解质浓度对溶胀行为的影响。结果表明,四种水凝胶中,N6040溶胀性能较好,在5 h即可达溶胀平衡,且在10-50℃时溶胀率无明显变化,对温度依赖性不强;溶胀时间对四种水凝胶溶胀率略有影响,但基本在4 h可以达到溶胀平衡;电解质溶液对水凝胶影响比较大,四种水凝胶的溶胀率均比在去离子水中明显降低。热重分析表明,该类水凝胶样品在低于230 ℃环境温度下非常稳定。 相似文献
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Complexes of polyvinylpyrrolidone–polyacrylic acid (PVP–PAA) photopolymerized from a mixture of PVP and acrylic acid (AA) were characterized by means of differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectrometry. The swelling of PVP–PAA semi-interpenetrating network (semi-IPN) films was studied in various pH media. The results showed that swelling in 0.1N HCl solution and pH 3.0 phosphate buffer was strikingly different from that in the pH 6.0 phosphate buffer. Caffeine release rate from the semi-IPN film followed Fick's Law. The rate of release was higher in dissolution media having pH above a critical value of about 3.8. Control of caffeine release from the semi-IPN film was realized by changing cyclically the pH of dissolution medium between 0.1N HCl solution and pH 6.0 phosphate buffer. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 921–930, 1998 相似文献