浊度法表征温敏性微凝胶体积的相转变行为

Volume Phase Transition Behavior and Stability of Temperature Sensitive Microgel by Turbidity Method

以N-异丙基丙烯酰胺(NIPAM)、甲基丙烯酸(MAA)为单体,N,N-亚甲基双丙烯酰胺(MBA)为交联剂,制备了温敏性聚(N-异丙基丙烯酰胺)(PNIPAM)和具有温度、pH敏感性的聚(N-异丙基丙烯酰胺-co-甲基丙烯酸)(PNIPAM-MAA)微凝胶。通过测定不同温度和pH条件下微凝胶浊度变化,表征微凝胶的温度及pH敏感性,描述了NaCl浓度和pH对微凝胶体积相转变温度的影响。同时,测定了微凝胶的临界聚沉浓度及临界絮凝温度,表征了微凝胶的稳定性,讨论了影响微凝胶的稳定性因素。

The thermo-sensitive and pH-responsive microgels were synthesized by soap-free polymerization, where N-isopropylacylamide and methacrylic acid as monomers, and N,N-methylenebisacrylamide as cross-linking agent. The thermo- and pH-sensitivities of microgels were evaluated by measuring the relative turbidity of microgel aqueous dispersions under varying temperature and pH. Meanwhile, effects of salt concentration and pH value on the volume phase transition temperature of microgels were estimated. The colloidal stability of microgels was characterized by examining the critical coagulation concentration and the critical flocculation temperature. Factors about microgel stability were discussed.