Anionic polyurethane ionomers including amphipathic nanoparticles were prepared by self-emulsifying method．When they were used as emulsifying agents to make styrene polymerize in them

anionic PS／PU nanocomposites dispersions with different PS／PU ratios(W／W)were prepared in situ．The polymerization process of styrene in polyurethane ionomers was studied．The sizes and distributions of the particles were measured by dynamic light scattering

and the structure and morphology of the nanocomposites were observed by transmission electron microscope．The results indicated that PS／PU nanocomposite emulsion with core-shell structure

based on anionic polyurethane as shell

polystyrene as core

was prepared

and when PS／PU ratios were higher than 50：100

some degree of particle aggregations happened．