Surface-grafted or cross-linked polystyrene(PS)/CaCO3 composite nanopartic les with nanometer CaCO3 as the core were synthesized by in situ emulsion polymerization.Subsequently

PS hollow nano-spheres were prepared by etching the core with dilute hydrochloric acid.The effects of the type and amount of emulsifier

the addition method of initiator and the feeding interval on emulsion stability

the yield and grafting efficiency were investigated.Composition and morphology of composite nanoparticles before and after etching were characterized by TGA

FT-IR and TEM.The results show that cationic emulsifier is in favor of the stability of emulsion system

and a higher yield and grafting efficiency can be achieved when using 3.7% ～ 5.5% cetyltrimethylammonium bromide (CTAB) as the emulsifier.With the amount of CTAB increased

the size of composite nanoparticles becomes smaller and the size distribution becomes broader.2

2′-azobisisobatyronitrile (AIBN)

the initiator

should avoid ultrasonic treatment along with monomers and CaCO3 particles

which may induce irreversible agglomeration.With the feeding interval prolonged

the yield and grafting efficiency decrease

and onepot method contributes to obtain composite nanoparticles with higher yield and grafting efficiency (or cross-linked degree).Although hollow particles can be prepared from either surface-grafted or cross-linked PS/CaCO3 composite particles by etching

the latter with cross-linked polymer shell have rather better size and shape stability and can retain their sphere shape after etching.