温度敏感聚(N-异丙基丙烯酰胺-co-甲基丙烯酰氧乙基二甲基辛基溴化铵)水凝胶的溶胀性能研究

由于改变亲水／疏水单体比值、与离子单体共聚心、改变凝胶内部结构等均可不同程度地调整温敏水凝胶的溶胀性能，本研究选择一种既含疏水烷基又含季铵盐正离子型亲水基团的两亲性单体——甲基丙烯酰氧乙基二甲基辛基溴化铵（ADMOAB），结构如示意图1所示．与N-异丙基丙烯酰胺（NIPAM）聚合，制备了P（NIPAM-co-ADMOAB）共聚水凝胶，以便在引入离子型结构单元的同时，改变凝胶体系中亲水／疏水单体比值，避免单纯增加疏水单体引起的水凝胶溶胀性降低问题，并考察了ADMOAB对水凝胶溶胀性能的影响，对该类水凝胶迄今鲜见相关文献报道．该研究对进一步了解水凝胶的构效关系、探索有效控制溶胀性能的途径具有积极意义．

SWELLING BEHAVIOR OF TEMPERATURE-SENSITIVE HYDROGELS BASED ON P(NIPAM- co-ADMOAB) POLYMERS

A series of poly(N-isopropylacrylamide-co-methacryloyloxyethyl dimethyloctyl ammonium bromide) [P (NIPAM-co-ADMOAB)] hydrogels were prepared.The influences of the amount of ADMOAB in copolymeric gels on the swelling behavior were investigated.The deswelling and reswelling kinetics were also studied.Results showed that the equilibrium swelling ratios (ESRs) of copolymeric gels increased with the enhanced ADMOAB content in the composition at temperatures below LCST,and the maximum ESR was 126 compared with a value of 28 for homopolymeric gel P(NIPAM),and the ESR for all copolymeric gels tended to zero independent of the composition when the temperature was above LCST.The rate constants in deswelling process increased at first and then decreased with increasing the ADMOAB amount,and the final water retention for copolymeric gels(about 1%) was much lower than that of P(NIPAM)(20%).The swelling ratios during reswelling process increased with the ADMOAB amount,and the diffusion of water into P(NIPAM-co-ADMOAB) gels was found to be a non-Fickian mode.Though decreased in saline solutions,swelling ratios for copolymeric gels were not significantly influenced by ionic strength with NaCl concentration from 0.1 to 0.3 mol/L and higher than those of homopolymeric gels in deionized water with the same swelling time.P(NIPAM-co-ADMOAB) hydrogels can be expected as good candidates for controlled drug delivery systems and separation processes.