Abstract: PS/Ag composite microspheres with core-shell structure were prepared by a seeded emulsion polymerization. The surface of PS/Ag microspheres as prepared was functionalized by PMMA. Its morphology and structure were characterized by TEM, XRD, TG, DTA and FT-IR, etc. The results show that Ag nanocore is spherical and its average diameter is about 12 nm. The average diameter of composite microphere is about 25 nm with a narrow size distribution. It is also found that composite nanoparticles can be well dispersed in organic solvent. Their tribological properties as additives in liquid paraffin were investigated with a four-ball tribometer. The results indicate, with the lubrication of liquid paraffin containing PMMA/PS/Ag nanoparticles, the wear-scar diameter is far smaller as compare with pure liquid paraffin. Moreover its maximum non-seizure load is above 1000 N and that of pure liquid paraffin is below 400 N. This shows that composite nanospheres have a good anti-wear performance.

Key words: Polystyrene/silver, Core-shell structure, Emulsion polymerization, 　Surface-functionalization, Tribological properties