Synthesis of polystyrene-silica nanoparticles via RAFT emulsifier-free emulsion polymerization

Abstract

Polystyrene-silica (PS-co-RAFT-SiO2) nanoparticles were synthesized via reversible addition-fragmentation chain-transfer (RAFT) emulsifier-free emulsion polymerization using poly (styrenesulfonate-sodium)-RAFT agent (macro-RAFT agent). The effects of macro-RAFT agent to initiator ratio on monomer conversion, particle size, particle size distribution, grafting efficiency and silica encapsulation efficiency were investigated. The particle size decreased with increasing macro-RAFT agent to initiator ratio ([R]:[I]). The PS-co-RAFT-SiO2 nanoparticles exhibited a size range of 23–56nm with a narrow size distribution for all polymerizations, ⩾99% monomer conversion was achieved. The PS-co-RAFT-SiO2 nanoparticles showed spherical particles with a core-shell morphology as confirmed by TEM photographs. The PS-co-RAFT-SiO2 nanocomposite could be used as filler in natural rubber. Accordingly, NR/PS-R-SiO2 blends had improved thermal and mechanical properties, and also exhibited good oil swelling resistance.