Syntheses of composite polystyrene latices with silica particles in the core

Abstract

A study of the synthesis of composite polystyrene latices with silica particles in the core has been performed under various conditions. It was apparent that the dense adsorption layer of hydroxyl propyl cellulose (HPC), which was formed on the silica particles at the lower critical solution temperature, plays a part in the preparation of the composite. When the bare particles of silica were used in the seeded emulsion polymerization, there was no tendency for encapsulation of the silica particles and, indeed, new polymer particles were formed in the aqueous phase. On the other hand, encapsulation of the seed particles proceeded preferentially when the HPC-coated silica particles were used as the seed and fairly monodisperse composite latices including silica particles were prepared. Furthermore, in the high concentration runs of the SDS, a new type of composite with a raspberry shape was generated with a high product yield. It is assumed that nucleation of new polymer particles would occur above the critical micelle concentration of the surfactant and that one portion of the new polymer particles would coagulate heterogeneously with the HPC-coated silica particles after some period of the seeded polymerization.