温敏性三元共聚水凝胶溶胀及消溶胀行为

Swelling and Deswelling Behavior of Temperature-Sensitive Terpolymer Hydrogels

采用自由基溶液聚合法,室温下制备了聚(N-异丙基丙烯酰胺-co-壳聚糖-co-甲基丙烯酸)[P(NIPAM-co-CS-co-MAA)]三元共聚水凝胶,以红外光谱及质量法对凝胶结构和溶胀性进行了表征。结果表明,高交联凝胶溶胀符合non-Fickian扩散;温度高于35℃时溶胀的共聚凝胶均发生明显收缩;相同甲基丙烯酸(MAA)和壳聚糖(CS)单体用量,MAA对凝胶溶胀和消溶胀影响大于CS。不同pH溶液中的溶胀碱性时比酸性条件下更大,pH=5.0左右较差,显示与传统甲基丙烯酸系水凝胶不同的pH敏感性,其消溶胀动力学满足一级动力学方程。

Terpolymer hydrogels of poly（N-isopropylacrylamide-co-chitosan-co-methacrylic acid）[P（NIPAM-co-CS-co-MAA）] were prepared by free radical solution polymerization at room temperature.The structure and swelling of the hydrogels were characterized by Fourier transform infrared spectroscopy and gravimetric method.The results indicate the swelling behavior of higher cross-linking hydrogels accords with non-Fickian diffusion mechanism,and the copolymer occurres prominently deswelling as temperature above 35 ℃.An obvious effect of monomers composition on swelling was confirmed by means of swelling experiments,and the swelling and deswelling transition arose from MAA to the terpolymer are greater than from CS under the same mass of MAA and CS monomers.For the swelling behavior of the hydrogels in various pH solutions,the swelling degree in alkaline solution exceeds in acidic medium,but it becomes bad in about pH=5.0 solution.This fact indicates that the hydrogels possess an anomalous pH-sensitivity,which differs from conventional methacrylic acid hydrogels,and the deswelling process is in very good agreement with first-ordered kinetics.