小分子液滴为模板制备有机-无机杂化纳米微胶囊

通过细乳液聚合,在正辛烷液滴外包覆一层苯乙烯与甲基丙烯酸-3-三甲氧基硅丙酯(MPS)的共聚物,制备了有机-无机杂化纳米微胶囊.通过透射电镜和动态光散射粒径仪观测其形态,用红外光谱表征了其分子结构.讨论了聚合方法对微胶囊制备的影响;通过溶度参数的计算和实验验证,发现配方中单体体积分数需小于36%才能得到微胶囊;通过界面自由能模型的计算和动力学分析,说明了微胶囊形成的热力学原因;发现共聚物中MPS的加入有利于微胶囊的形成,但若MPS的含量过大将会导致胶囊塌陷;最后阐明了这种微胶囊制备过程的机理.

Synthesis of Organic-inorganic Hybrid Nanocapsules by Using Low Molecular Weight Droplets as Template

A novel nanocapsules were synthesized by miniemulsion polymerization the using low molecular weight droplets as the template. Styrene and 3-trimethoxysilyl propyl methacrylate(MPS), which contain vinyl and Si—OR groups, are copolymerized on the surface of the well dispersed isooctane droplets to form capsules. With the free radical copolymerization, the Si—OR groups can be hydrolyzed and condensed into Si—O—Si inorganic network. The diameter of the capsules is about 98 nm and the void fraction is about 70%. The morphology of the capsules was characterized by transmission electron microscopy, and the microstructures of the capsules were characterized by infrared spectrometry. The effects of the polymerization methods and monomer volume fraction on the morphology were discussed. It is found that the initial volume fraction of the monomer in the recipe must be lower than 36% to obtain capsules, and higher MPS volume fraction is favor in the formation of capsules, but a higher MPS content in capsules will lead to collapse. Finally, the mechanism of this synthetic process was interpreted by thermodynamic and kinetic analysis.