The organic montmorillonite VC18-MMT was prepared by the exchanging inorganic cations with vinylbenzyldimethyloctadecylammionun chloride (VOAC) which could be co-polymerized with styrene.The predispersion of VC18-MMT was realized via sonicating the suspension of the montmorillonite particles in emulsifier solution

and then the styrene was added into the system and the in situ emulsion polymerization was carried out to prepare PS/VC18-MMT nanocomposites.The structure of final nanocomposites was characterized by XRD and TEM.The results indicated that the most of montmorillonite was fully exfoliated into individual layers and uniformly dispersed in the polystyrene matrix.The dynamic mechanical properties of the nanocomposites were determined by DMA

which demonstrated that the storage modulus and glass transition temperature of polystyrene were increased by compositing of montmorillonite.The polymer grafted on the layers of montmorillonite could be obtained by ion exchanging with lithium cations.The structure and average molecular weight of the polymer were characterized by NMR and GPC.The results showed that the polymer grafted on layers of montmorillonite was identifed as the copolymer of styrene with VOAC and the average molecular weight of the copolymer was lower than that of free polystyrene.One copolymer chain averagely comprised about 25 VOAC molecules

which can be calculated through the concentration of VOAC and the mass of copolymer in the galleries of montmorillonite.