The monodisperse SiO2-coated polystyrene (PS) (PS/SiO2) core-shell nanocomposite microspheres were prepared by a simple and low-cost method.The PS nanospheres were first synthesized in the presence of polyvinylpyrrolidone (PVP)

and the SiO2 particles were subsequently coated on the surface of the PS nanospheres by sol-gel process in NH4OH/ethanol solutions.The preparation of the PS nanospheres is accomplished in aqueous media and has following advantages:no comonomer is needed

the cheap potassium persulfate (K2S2O8) radical initiator is used instead of the expensive azodiisobutyramidine dihydrochloride (AIBA) radical initiator

and no exchange of the solvent and no centrifugal process are needed before the process of coating the SiO2 particles on the PS nanospheres.The influences of the content of the PVP

NH4OH

and tetraethyl orthosilicate (TEOS) on the size and morphology of the PS/SiO2 nanocomposite microspheres were investigated.With increasing the content of PVP

the size of the PS nanospheres decreased

and thus smaller PS/SiO2 nanocomposite microspheres were obtained.The content of NH4OH did not affect the thickness of the SiO2 shell

bus it influenced the morphology of the SiO2 shell.The surface of the SiO2 shell changed from smoothness to roughness with increasing content of NH4OH.With increasing content of TEOS

the generated SiO2 particles increased

and thus the thickness of the SiO2 shell increased.