Study On The Preparation Of SiO₂Composite Materials By ATRP In Water Medium

Silica nanoparticle is one of the most studied nonmetal oxide for various applicationsranging from ultraviolet light absorber, photocatalyst, and gas sensors, etc. As othernanomaterials, agglomeration of SiO2nanoparticles has been the most obstacles in their wideapplications. The traits of nanoparticles are hardly embodied in usage because they areusually dispersed in medium in aggregation of micro-size. So the study of improvingdispersivity of nano-silica in organic solvents has raised considerable interest recently.In this paper, nano-silica was pre-treated with vinyl-silane coupling agent, and thenSiO2/PMMA composite particles were prepared by reverse atom transfer radicalpolymerization(RATRP) with CuCl2as catalyst、TMEDA as ligand and ASP as initiator inwater medium. The effects of some factors, such as temperature、weight ratio of monomers toSiO2、molar ratio of monomers to initiators、molar ratio of catalysts to ligand and stirringspeed, on polymerization rate of monomers were investigated and the process condition ofpolymerization was determined. In addition, the partition coefficient of catalyse systembetween the MMA phase and water phase was measured respectively, and polymerizationtheory was discussed primarily. The polymerization rate of monomers was determined bymeans of gravity. The framework vibration bands of untreated and treated nano-silica particleswere characterized by FTIR. The gravity percent of polymethyl methacrylate was decided byTGA. The dispersion capacity of nano-SiO2and composite particles were observed by TEM.The diameter distribution of nano-silica modified or not was measured by LSS. Molecularweight and molecular weight distributions of polymer were measured on GPC. The partitioncoefficient of catalyse system between the oil phase and water phase was measured byUV-Vis.The results show that the preparation of SiO2/PMMA composite particles was possible byRATRP in water medium. The operating parameters for preparing SiO2/PMMA compositeparticles: reaction temperature75℃、weight ratio of MMA to SiO22：1、molar ratio of MMAto initiator200：1、molar ratio of catalyst to ligand1：3、stirring speed1125r/min。SiO2/PMMA composite particles have a smaller diameter distribution and better dispersion effect, so the agglomeration problem of nano-silica was settled in certain extent. The gravitypercent of polymethyl methacrylate was29.91%. CuCl/TMEDA and CuCl2/TMEDA havedifferent partition coefficient between the MMA phase and water phase. The controlledradical compared to all of radica was3%through theory analysis。...