Revisiting the Classical Emulsion Polymerization: An Intriguing Occurrence of Monodispersed Bowl-Shaped Particles

Abstract

An intriguing phenomenon is found that monodispersed bowl-shaped rather than spherical poly(styrene-co-butyl acrylate) [P(St-co-BA)] particles can be obtained by one pot traditional emulsion polymerization without using any template or redundant process and the cavity size is controllable. The facile implementation method is beneficial to large-scale fabrication of the bowl-shaped particles. Herein, the amphiphilic oligomeric radical with hydrophobic P(St-co-BA) chains and hydrophilic sulfate groups ([−OSO3]−) from water-soluble potassium persulfate could migrate to surface of primary latex particles to act as an emulsifier when amount of the additional emulsifier is so low, which causes an imbalance between inside and outside osmotic pressures of the latex particles to result in bowl-shaped particles for the kinetic stability. This advances the understanding of classical emulsion polymerization mechanism.