A negatively charged PSt seed latex was first synthesized via batch emulsifierfree emulsion polymerization

and the PSt particles were then dispersed into the medium of ethanol and water

and γaminopropyltriethoxysilane (KH550) was added to modify the particle surface at 25℃ to prepare the positively charged and silylated PSt particles.Finally

the coreshell PSt/SiO2 composite microspheres were obtained by dropwise adding tetraethoxysilane (TEOS) into the above system under alkaline condition.Influences of KH550 amount on zeta potential of PSt seed latex

and influences of reaction time and EtOH/H2O ratio on the morphology of PSt/SiO2 composite microspheres were investigated.Results showed that zeta potential of PSt seed latex increased with increasing the KH550 amount

and reached its optimum value of 38 mV from -345 mV when the amount of KH550 was increased to 1/3 of PSt seed weight.In the preparation of coreshell PSt/SiO2 composite microspheres

the encapsulation ratio of SiO2 onto the modified PSt particles increased with the increasing reaction time

and maximum value of 979% achieved when the reaction time prolonged to 24 h;With the decrease of EtOH/H2O

the number of SiO2 nanoparticles absorbed onto the composite microspheres decreased

and the uniform coreshell PSt/SiO2 composite microspheres with the shell thickness about 35 nm were obtained in the medium with EtOH/H2O weight ratio of 60/285