Poly(styrene/hydroxypropyl methylcellulose phthalate) latex particles prepared by resin-fortified emulsion polymerization

Cellulose is a natural and biodegradable polymer with abundant hydroxyl groups, which can be utilized as functional moieties in the various chemical modification of cellulose polymer. Among the cellulose derivatives, hydroxypropyl methylcellulose phthalate (HPMCP) has both hydroxyl and carboxyl groups. It could be dissolved into water phase to form aggregates, like micelles, under basic conditions. In this study, a reactive HPMCP, which has carbon double bonds, was synthesized using a stepwise reaction with isophorone diisocyanate (IPDI) and 2-hydroxyethyl methacrylate (HEMA). It was used as both a counter-polymer and a reactive surfactant in the emulsion polymerization of styrene. For comparison, the emulsion polymerizations of styrene with pristine HPMCP and reactive HPMCP were carried out under the same polymerization condition. Reactive HPMCP is a sort of surface active macro-monomer; thus, it can grow polystyrene polymeric radicals on its backbone. Due to the presence of carbon double bonds in the reactive HPMCP, two kinds of HPMCP-modified polystyrene latex particles showed significant differences in the particle size evolution, latex viscosity, particle morphology, and thermal properties.