Preparation of “hard-soft” Janus polymeric particles via seeded dispersion polymerization in the presence of n-paraffin droplets

Abstract

A newly emerged class of Janus polymer particles, so-called “hard-soft” ones, were produced using seeded dispersion polymerization (SDP) of 2-ethylhexyl methacrylate (EHMA) with polystyrene (PS) particles in the presence of n-paraffin droplets. It was found that the presence of n-paraffin in the medium does not have any effect on the shape of the seed particles, but it changes the distribution of poly(ethylhexyl methacrylate) (PEHMA) domains on the surface of them from symmetric to asymmetric, resulting in the production of Janus composite particles. The effect of various polymerization conditions (e.g. type of the hydrocarbon, monomer concentration, n-paraffin content, amount of initiator, methanol–water weight ratio, stabilizer content, type of second monomer, and size of seed beads) on the shape of the final particles was investigated. From all of the obtained results, it was concluded that the size and concentration of precipitated PEHMA oligoradicals coupled with the presence of n-paraffin are the main parameters responsible for the production of Janus polymer particles.