POLYMER-CLAY NANOCOMPOSITES - FREE-RADICAL GRAFTING OF POLYSTYRENE ONTO ORGANOPHILIC MONTMORILLONITE INTERLAYERS

Vinyl monomer-montmorillonite intercalates, which are able to swell an d disperse in organic solvents, have been prepared by a cation exchang e process by the interaction between the Na+ or Ca2+ cations of montmo rillonite and vinylbenzyltrimethylammonium chloride. The resulting vin yl monomer-montmorillonite materials have been identified by X-ray dif fraction (XRD), elemental analysis and infrared absorption spectra. Fr ee-radical solution polymerizations of the penetrated styrene between the interlayers of 5, 10, 25 and 50 wt% vinyl monomer-montmorillonite have resulted in grafted polystyrene-montmorillonite materials. The ef fect of montmorillonite amounts on the formed polystyrene was determin ed by extraction with organic solvents, which showed an increase in th e grafted polymer formed (0.84-2.94 g/g MMT), and a decrease in the ex ternal polystyrene with increasing amounts of montmorillonite. The mol ecular weight of the external polystyrenes was found to be in the rang e of 22 000. The vinyl monomer-montmorillonite and polymer-montmorillo nite intercalates have been identified by XRD, elemental analysis and infrared spectroscopy. Examination of the polystyrene-montmorillonite materials by SEM, TEM and XRD showed spherical particles of nanosize a bout 150-400 nm, and basal spacings of 1.72-2.45 nm.