温敏性含氟两亲接枝共聚物的制备及胶束化行为

以聚乙二醇单甲醚甲基丙烯酸酯(MPEGMA)为大分子单体, 甲基丙烯酸六氟丁酯(HFMA)为含氟单体, N-异丙基丙烯酰胺(NIPAAm)为功能性单体, 采用大分子单体接枝共聚法, 制备了一种温敏性含氟两亲接枝共聚物P(NIPAAm-co-HFMA)-g-PEG. 利用FTIR, ¹H NMR, ¹⁹F NMR和GPC对共聚物的结构进行表征; 采用紫外-可见分光光度计测定了共聚物的低临界溶解温度(LCST)约为38.9 ℃, 高于人体正常的生理温度; 利用荧光探针技术测定了共聚物的临界胶束浓度(cmc), 结果表明, 当共聚物溶液温度高于LCST时, 其cmc明显变小; 利用激光光散射粒度仪(LLS)测定了共聚物胶束的水合粒径及其分布, 当温度达到LCST时, 胶束粒径明显变小, 温度过高时, 粒径又有所增大; 利用透射电子显微镜(TEM)研究了共聚物胶束的形貌, 结果表明, P(NIPAAm-co-HFMA)-g-PEG在水溶液中可自组装成球状胶束粒子, 随着温度的升高, 共聚物胶束由松散的核壳结构转变成更加紧凑的球状结构, 且粒径明显变小.

Preparation and Research on Micellization Behavior of Thermo-sensitive Fluorine-containing Amphiphilic Graft Copolymer

The novel thermo-sensitive fluorine-containing amphiphilic graft copolymer was prepared by graft copolymerization of poly(ethylene glycol) methyl ether methacrylate(MPEGMA) macromonomer,2,2,3,4,4,4-hexafluorobutyl methacrylate(HFMA) and N-isopropylacrylamide(NIPAAm).The molecular structures of the graft copolymer were characterized by FTIR,1H NMR,19F NMR and gel permeation chromatography(GPC).The low critical solution temperature(LCST) was measured by UV-Vis spectrophotometer.The result shows that the LCST is about 38.9 ℃ and above the normal human physiological temperature.The critical micelle concentrations(cmc) were determined by the fluorescent probe technique.When the copolymer aqueous solution temperature was above the LCST,the cmc decreased significantly.The average hydrodynamic radius and size distribution of the copolymer micelles were measured by laser light scattering(LLS).The micelle size decreased greatly when the copolymer aqueous solution temperature reached the LCST.However,when the temperature was too high,the micelles became larger instead.The morphology of the copolymer micelles was observed by transmission electron microscopy(TEM).The result shows that P(NIPAAm-co-HFMA)-g-PEG can self-assemble into spherical micelles.When the temperature was under the LCST,the micelles had a loose core-shell structure.When the temperature was above the LCST,the micelle became compact and the core-shell structure was not obvious.In a word,the micelles were sensitive to the change of temperature.