Abstract: Core/shell composite microparticles with silica nanoparticle as core and crosslinked poly (tert-butylmethacrylate) as shell were prepared by seed-emulsion polymerization utilizing 3-(trimethoxysilyl) propyl methacrylate (MPS) modified silica particles as seeds,tert-butylmethacrylate as monomer and sodium dodecyl sulfate (SDS) as emulsifier.The microparticles were transformed into pH-sensitive inorganic/organic composite microparticles by hydrolysis.The factors affecting the morphological structure of the composite microparticles were investigated,and it was found that the formation of pure poly (tert-butylmethacrylate) latex particles in the polymerization process could be avoided by controlling the solid content of the silica seed emulsion in the range from 1.5% to 2%.Pure poly (tert-butylmethacrylate) latex particles tended to be formed when the content of SDS exceeded 0.3%,while the core/shell composite microparticles were readily flocculated if the content of SDS was below 0.15%.Their shell thickness was enhanced as the amount of the monomer and crosslinker was increased,but their excessive use led to the formation of pure poly (tert-butylmethacrylate) latex particles and the flocculation of the formed core/shell composite microparticles.The core/shell morphological structure and chemical composition of the composite microparticles were confirmed by TEM,NMR,FTIR and contact angle analysis results.