阳离子化热响应微凝胶的合成及在二氧化硅矿化中的应用

采用无皂乳液聚合技术,在亚甲基双丙烯酰胺(MBA)为交联剂的情况下,N-异丙基丙烯酰胺(NIPAM)与甲基丙烯酰氧乙基三甲基氯化铵(DMC)发生共聚,生成具有阳离子功能化的热响应微凝胶poly-(NIPAM-co-DMC).TEM研究表明该微凝胶粒子的粒径约为200 nm左右,具有规则的球形形态.DLS和1H-NMR研究证实了微凝胶粒子的最低临界溶液温度(LCST)在34℃左右.进一步以此微凝胶为模板,在中性条件下,以四甲氧基硅烷(TMOS)为硅源,在此模板上仿生沉积S iO2,生成poly(NIPAM-co-DMC)/S iO2杂化纳米粒子.FTIR、TEM、1H-NMR及TGA等研究表明S iO2在聚合物模板上发生了沉积.能谱分析进一步证明了S iO2主要分布在杂化纳米粒子的壳层区域.另外,当矿化反应温度高于微凝胶的LCST值时,体系生成了具有明显核壳结构的异形杂化粒子.

SYNTHESIS OF CATIONIC THERMO-RESPONSIVE MICROGELS AND THEIR APPLICATION FOR BIOMIMETIC MINERALIZATION OF SILICA

Cationic thermo-responsive microgels of P(NIPAM-co-DMC)were synthesized by copolymerizing mononers of N-isopropylacrylamide(NIPAM)and 2-methylacryloyloxyethyhrimethyl ammonium chloride (DMC)in the presence of a crosslinker N,N'-methylene-bis-acrylamide(MBA)by soap-free emusion polymerization.TEM observation indicates that the average diameter of copolymer microgels is about 200 nm.The lower critical solution temperature(LCST)of the prepared mierogel is estimated to be about 34℃ by both DLS and ~1H-NMR measurements.This cationic microgel was further used as a colloidal template for biomimetic mineralization of silica.The silica deposition was performed by simply stirring a mixture of aquous solution of microgel and TMOS at room temperature and neutral pH.The combination of FTIR,TEM,~1H-NMR and TGA characterizations indicated that silica mainly deposited on the shell region of microgels.Moreover,we observed that hybrid nanoparticles with shringaged shape were formed when the silicification was performed at 40℃.