Admicellar polymerization of styrene with divinyl benzene on alumina particles: the synthesis of white reinforcing fillers

Admicellar polymerization has been used to form polymer coated white mineral particulates as alternatives to carbon black for application in rubber reinforcement. An ultra thin film of polystyrene and cross-linked with divinylbenzene was used to coat alumina particles. Optimization of reaction conditions was carried out, through investigation of factors that affect the adsorption of the surfactant, sodium dodecyl sulfate, on alumina and film formation. The surface modified particles were characterized using ultraviolet absorbance, thermogravimetry, scanning electron microscopy, and changes in hydrophobicity were determined qualitatively using a drop test. Results showed that alumina particles were successfully coated with poly(styrene-co-divinylbenzene), and their resistance to wetting by water was greatly enhanced after admicellar polymerization treatment.