Heterogeneous polymerization with polyaspartate macromonomer having vinyl pendant groups. I. Synthesis of macromonomer and dispersion copolymerization of styrene

Sodium polyaspartate (PAspNa) derivatives with vinylbenzyl pendant groups (VBA-PAspNa) were synthesized by reaction of poly(succinimide) (PSI) and vinylbenzylamine (VBA), and hydrolysis by sodium hydroxide (NaOH) solution. VBA-PAspNa is a macromonomer with multiple vinyl groups in the side chain. Submicron sized polymeric particles were prepared by dispersion copolymerization of styrene with VBA-PAspNa in a mixture of ethanol and water. Particle diameter decreased with increasing concentration and vinyl group fraction of VBA-PAspNa. When compared with the particle diameter prepared using PAspNa or benzylamine-modified PAspNa (BA-PAspNa) as a dispersion stabilizer without vinyl groups, the particles prepared with VBA-PAspNa were an order smaller than those prepared with PAspNa or BA-PAspNa. The particles after refinement show an adequate negative ζ-potential. From this result, we clarified the presence of PAspNa chains anchored onto the particle surface.