Polymer-clay nanocomposites: exfoliation of organophilic montmorillonite nanolayers in polystyrene

A polymerizable cationic surfactant, vinylbenzyldimethyldodecylammonium chl oride (VDAC) was synthesized for functionalization of montmorillonite (MMT) and preparation of exfoliated polystyrene-clay nanocomposites. Organophili c MMT was prepared by cationic exchange between inorganic ions of MMT and a mmonium cations of VDAC in an aqueous medium. Dispersions of intercalated c lay (VDAC-MMT) in styrene monomer formed gels. Shear thinning behavior of t he gels was observed via rheological measurements. Polystyrene-clay nanocom posites were prepared by free radical polymerization of styrene containing dispersed organophilic MMT. Exfoliation of MMT in polystyrene matrix was ac hieved as revealed by X-ray diffraction (XRD) and transmission electron mic roscopy (TEM). The exfoliated nanocomposites have higher dynamic modulus an d higher decomposition temperature than pure polystyrene. (C) 2000 Elsevier Science Ltd. All rights reserved.