Preparation of polystyrene colloid particles armored by clay platelets via dispersion polymerization

Polystyrene colloid particles armored by Montmorillonite clay (MMT) were prepared by free-radical polymerization in dispersion. MMT was pre-modified with cationic amphiphilic block copolymer of poly(styrene-b-2-hydroxyethyl acrylate) (PS-b-PHEA), and the obtained (PS-b-PHEA)-MMT modified clay was used as stabilizer in dispersion polymerization. The impact of (PS-b-PHEA)-MMT loading on the particle size, the monomer conversion, and on the molecular weight were investigated. The main objective of this paper was to use the clay platelets as stabilizers in dispersion polymerization, and as nanofiller to improve some polymer properties such as thermal stability, thermo-mechanical and melt flow properties. Transmission electron microscopy (TEM) showed that colloid PS particles with MMT layers at the surface (i.e. armored particles) were obtained, and the particles sizes were found to be in the micrometer size range and stable dispersion were obtained for clay loadings up to 5wt%. Small angle X-ray diffractions (XRD) and TEM revealed that polymer-clay nanocomposites (PCNs) with partially exfoliated structures were obtained for low clay loading, while intercalated structures were obtained at higher clay loading. All PCNs were found to be more thermally stable than neat polymer as were determined by TGA. Furthermore, an increase in the storage modulus and the T-g of the PCNs was found and greatly correlated to the clay loading. (C) 2011 Elsevier Ltd. All rights reserved.