Janus微球的制备及其性能

以Pickering乳液为基础，设计了一种制备非球形单分散Janus颗粒的方法，对一端镶嵌在石蜡上的纳米二氧化硅微球进行不对称刻蚀，通过控制刻蚀时间，得到不同性质的Janus微球. 首先，利用凝胶-溶胶法，在水醇体系中，以正硅酸四乙酯（TEOS）为硅源、氨水作为催化剂，合成SiO₂微球. 然后，利用硅烷偶联剂3-胺丙基三乙氧基硅烷（AMPTS）对SiO₂胶体表面进行-NH2修饰，于石蜡水界面制备一端被石蜡包裹的Pickering粒子. 利用不同质量分数的NH4F溶液对pickering粒子暴露端进行刻蚀，去掉表面的氨基修饰成分. 对石蜡保护端用酰氯修饰，并与NIPAM进行接枝聚合，最终得到兼有有机/无机性质并具有温敏性的聚合物PNIPAM/SiO₂ Janus微球. 对其进行乳化性能及温敏性测试， 结果表明，与原始Janus微球相比，接枝改性后的PNIPAM/SiO₂ Janus微球作为乳化剂得到的乳液体系更稳定.

Preparation and Its Property of Janus Microsphere

A method for synthesizing monodisperse nonspherical Janus particles was designed based on the Pickering emulsion.The Janus microspheres were prepared by asymmetric etching on the silica particles with one end embedded in wax. The Janus microspheres with different properties were obtained through controlling different etching times. Firstly， the spherical silica microspheres were prepared through the sol-gel method in Ethanol/water system， using ammonia as catalyst and tetraethyl orthosilicate （TEOS） as a silica source. Then， the silica surface was modified by silane coupling agent 3-aminopropyl triethoxysilane （AMPTS） to obtain the amino group. The modified silica spheres were placed on the interface of water and wax and then the Pickering particles with one end wrapped by wax were prepared. The exposed end of the Pickering particles was etched at different mass fraction of NH4F solution to remove the amino modified part. The wax protected end was modified by acyl chloride group to carry out the graft polymerization with NIPAM. Therefore， the temperature-sensitive PNIPAM-SiO₂ Janus microsphere with both organic and inorganic properties was obtained. Their emulsion performance and temperature sensitivity were tested. The results indicate that the emulsion formed by the grafted PNIPAM-SiO₂ Janus particles show better stability than that formed by the initial Janus particles.