一种新型有机-无机杂化微胶囊及其渗透性

Penetrating properties of novel organic-inorganic hybrid nanocapsules

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,得到一种新型有机-无机杂化纳米微胶囊.用透射电镜(TEM)和原子力显微镜(AFM)表征了其形态;用气体吸附仪(BET)研究了其微观结构,发现其具有多孔结构.利用多孔介质中的孔道扩散理论对其渗透过程进行建模,微胶囊渗透过程中的主体扩散系数主要由其孔隙率和曲折因子决定.用紫外可见分光光度计(UV)研究了微胶囊在不同体系中的渗透动力学,计算得到了各种条件下渗透的主体扩散系数和曲折因子,发现溶质的扩散速率随微胶囊中MPS用量增加造成的孔隙率增大而增加;曲折因子在甲酚红-甲醇体系中比在蒽-四氢呋喃体系中小,且基本不随微胶囊中MPS用量变化,与用孔道扩散理论分析结果一致.用红外光谱(IR)证实了示踪剂确实装载进入了微胶囊,但示踪剂的释放速率比装载速率小得多,且主体扩散系数随MPS用量变化不大.

A novel organic-inorganic hybrid nanocapsule was synthesized by mini-emulsion copolymerization of styrene and 3-trimethoxysilyl propyl methacrylate （MPS） on the well dispersed octane droplet templates. The morphology was characterized by transmission electron microscopy （TEM） and atom force microscopy （AFM）. The microstructure parameters were characterized by gas adsorption instrument. The wall of the capsules was found to have microporous structures. According to these characteristics, a penetration model was established by using the percolation theory. The penetration diffusion coefficient was dependent on porosity and tortuosity. The kinetics of the penetration process was studied with ultraviolet-spectrophotometer and diffusion coefficient and tortuosity were calculated. Diffusion velocity increased with the increase of MPS content in capsules due to larger porosity; tortuosity was less in the cresol red-methanol system than in the anthracene-tetrahydrofuran system; and tortuosity nearly did not change with the MPS content in capsules. All these results were consistent with the percolation theory. The loading of the anthracene was also proved by infrared spectrometry, and the release diffusion coefficient was much smaller than that of loading, but did not change with the MPS content in capsules.