Preparation And Application Of Janus SiO₂ Colloidal Particles

With the development of society and scientific progress,anisotropic particles（Janus particles）with different chemical properties and asymmetry structures have aroused great interest.Janus particles have broad application prospects in the fields of physics,chemistry,and biomedicine,etc.Therefore,it is of great significance to design anisotropic particles with asymmetric structures and chemical properties.The SiO₂ nanoparticles are often used to prepare anisotropic particles because of their high chemical stability,unique biocompatibility,good radiation resistance,excellent acid-base resistance,and the ability to absorb ultraviolet rays.This article focuses on the preparation of Janus SiO₂ colloidal particles with asymmetric micro-morphology and chemical properties.The main research contents are as follows:1.We prepared SiO₂@PS strawberry-like Janus composite microspheres with inorganic SiO₂as the core particles,polystyrene（PS）as the surface convex particles by soap-free emulsion polymerization of seeds.The morphology of SiO₂@PS strawberry-like Janus composite microspheres was controlled by changing the solvent ratio,monomer feed ratio,and reaction time.Moreover,we explored the effects of organic solvent types,reactive monomer types,and SiO₂ particles surface hydroxyl groups on strawberry-like composite microspheres.Furthernore,we used the SiO₂@PS strawberry-like Janus composite microspheres as template particles,and we obtained the bowl-like PS nanoparticles by selective etching SiO₂ particles.2.We designed and prepared silica@mercaptopropyl polysilsesquioxane（SiO₂@MPSQ） snowman-like Janus composite particles with SiO₂ particles as seeds.Furthermore,the SiO₂@MPSQ were used as template particles,which not only obtained bowl-like MPSQ particles by removing SiO₂ nanoparticles,but also changed the physicochemical properties of SiO₂@MPSQ snowman-like Janus composite particles by the click reaction between the mercapto group and the carbon-carbon double bond using methyl methacrylate or methyl acrylate.In addition,the particle morphology were adjusted by changing the amount of MPTMS added and the type of silane coupling agent,meanwhile the effects of the solubility and etching time of HF solution on the morphology of bowl-like MPSQ particles were investigated.3.Based on PS@SiO₂ core/shell composite microspheres,we prepared Janus SiO₂microcapsules by regional modification and template removal.Acidic groups on the inner surface and basic groups on the outer surface modified the SiO₂ microcapsules.The catalytic performance of open-mouthed SO₃H-SiO₂-NH₂ microcapsules was investigated by acid-base cascade catalysis.