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气液界面阳离子型Gemini表面活性剂-硬脂酸混合单分子膜性质

ISSN号：1006-3080
期刊名称：《华东理工大学学报：自然科学版》
时间：0
分类：O633.22[理学—高分子化学;理学—化学] TE357.46[石油与天然气工程—油气田开发工程]
作者机构：[1]华东理工大学化学系结构可控先进功能材料及其制备教育部重点实验室,上海200237, [2]上海应用技术学院化工系,上海200235
相关基金：国家自然科学基金（Nos.20606010,20476025,20490200）和上海市重点学科建设（No.P1501）资助项目.

关键词： N-异丙基丙烯酰胺, 微凝胶, 温度敏感性, 稳定性, N-isopropylacrylamide, microgel, temperature sensitivity, stability

中文摘要：

用沉降聚合法制备了聚（N-异丙基丙烯酰胺-co-甲基丙烯酸）微凝胶，并用NMR，DLS分析测定了微凝胶结构及凝胶颗粒在不同离子强度下粒径和表面电势的变化,25℃时在pH=7的溶液中Zeta电位为-18mV，随离子强度增加，逐渐减小，当NaCl浓度达0．2mol／L时基本不变，表明微凝胶表面电荷受到屏蔽，浓度继续增加主要使凝胶颗粒收缩，加热引起微凝胶收缩，颗粒表面电荷密度增大，Zeta电位增大，在0．2mol／L NaCl溶液中，41℃时微凝胶的Zeta电位可达-12．4mV，使微凝胶稳定，较高离子强度时，Zeta电位随温度升高发生突变，微凝胶表面几乎为中性，其突变温度与临界絮凝温度（CFT）相当，CFT随离子强度增加向低温迁移，微凝胶聚集速率在高温时比低温时快。

英文摘要：

Poly（N-isopropylacrylamide-co-methacrylic acid） microgel was prepared by the precipitation polymerization method. NMR and TEM were used to analyze microstructure and morphology of the microgel. The stability and zeta potential of the microgel were investigated as a function of electrolyte concentration by dynamic light scattering. Zeta potential was -18 mV in pH=7 solution at 25 ℃, which decreased gradually with increasing ionic strength and reached an equilibrium value at 0.2 mol/L NaCl concentration, indicating that the surface charge of the microgel had been screened out. Increasing in NaCl concentration caused mainly the microgel particles to shrink. For the microgel in certain electrolyte solution, the heating induced the particles to deswell. As a result, the surface charge density became greater gradually,resulting in the increase of zeta potential. For microgel in 0.2 mol/L NaCl solution, the zeta potential was -12.4 mV at 41℃, playing an important role in stabilizing the microgel. The potential of the microgel at higher ionic strength displayed an abrupt transition of trending to zero as increasing the temperature, and the relevant temperature was correspondent with the critical flocculation temperature （CFT）. The CFT of the microgel was shifted to lower temperature with the increase of NaC1 concentration. At a certain salt concentration, the aggregation rate of the particles at a higher temperature was faster than that at a lower temperature.

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