Supported initiator was synthesized by exchange of Na+ and initiator 2

2'-azobis(2-methylpropion-amidine)dihydrochloride(AIBA)．The MMT-supported initiator was used to initiate the emulsion polymerization of styrene and prepare PS／MMT nanocomposite．The clay-supported initiator and the structure of PS／MMT nanocomposite were characterized by XRD

TGA

DSC

TEM and extraction method．The results indicated the successful intercalation of initiator molecules in the galleries of clay layers since the MMT-supported initiator showed increased d-spacing values and more weight loss in the temperature range of 200～600℃．During polymerization

the initiator intemalated in the layers of MMT decomposed to produce radicals that initiated the polymerization of styrene．The decomposition of initiator also caused the exfoliation of MMT layers．In the PS／MMT emulsion

the layers of MMT were adhered on the surface of polymer particles．The final nanocomposites were formed by coagulation and melting．In nanocomposites

the layers of MMT were uniformly dispersed in polymer matrix．Some MMT layers were fully exfollated into individual ones

and the others dominantly existed as nano—aggregates with thickness of around 10～20 nm．The results of extraction experiment showed that a great deal of PS chains was grafted on the layers of MMT．The molecular weight and molecular weight distribution of PS grafted on the layers of MMT were different from those of tlle freeps polymer．