Emulsion polymerization using three types of RAFT prepared well-defined cationic polymeric stabilizers based on 2-dimethylaminoethyl methacrylate (DMAEMA): a comparative study

Abstract

Three types of well-defined stabilizers, based on 2-dimethylaminoethyl methacrylate (DMAEMA), including poly(2-dimethylaminoethyl methacrylate) (PDMAEMA), poly(2-dimethylaminoethyl methacrylate)-block-poly(methyl methacrylate) (PDMAEMA-b-PMMA), and PDMAEMA-co-PMMA, were synthesized through reversible addition-fragmentation chain transfer (RAFT) solution polymerization and used as well-defined cationic stabilizers in emulsion (co)polymerization of styrene and/or methyl methacrylate (MMA). Because of different characteristics of MMA and styrene, using varying ratios of these monomer as well as using different structures of stabilizers allowed us to better understanding of stabilizers’ behavior during polymerization course. The results showed that PDMAEMA-b-PMMA was more robust against changes in monomer composition, meaning less fluctuations in particle size distribution and kinetics plots. Also, more than 85% monomer conversion was reached and the resulting polymer particles, ranging in diameter from 75 to ~135 nm. Using PDMAEMA-b-PMMA and adding only 5 mol% MMA as a comonomer in emulsion polymerization of styrene resulted in producing highly uniform particles with size polydispersity of (0.04), as confirmed by TEM and DLS. This narrow size polydispersity was attributed to generation of more positively charged amphiphilic oligomers at early stages of polymerization and thus, faster nucleation.