Controlled Synthesis of Nano-Sized Cationic Soap-Free Polystyrene/Poly(methyl methacrylate) Latexes via Reversible Addition-Fragmentation Chain Transfer Mediated Emulsion Copolymerization

摘要

In this paper, nano-sized cationic polystyrene(PS)/poly(methyl methacrylate) (PMMA) composite latex was prepared through emulsion reversible addition-fragmentation chain transfer (RAFT) copolymerization of styrene and methyl methacrylate mediated by the cationic poly[N-(4-vinylbenzyl)-N,N-dibutylamine hydrochloride] trithiocarbonate (PVBAH-TTC) surfactant macro-RAFT agent. The influences of emulsion solid content, molar ratio of macro-RAFT agent to monomer, and the molecular weight of PVBAH-TTC macro-RAFT agent on the RAFT emulsion copolymerization are explored. Well-controlled polymerization with fast polymerization rate, high monomer conversion and little coagulum can be achieved under the condition of emulsion solid content below 40%, the molar ratio of macro-RAFT agent to monomer lower than 1:600, and the molecular weight of PVBAH-TTC macro-RAFT agent ranging from 4.7 to 10.5 kg/mol. The polymerization led to formation of well-defined nano-sized cationic colloids of the poly[N(4-vinylbenzyl)-N,N-dibutylamine]-b-poly(styrene-co-methyl methacrylate)-b-poly[N-(4-vinylbenzyl)N,N-dibutylamine] triblock copolymer. The colloids generally have core shell structure, in which the hydrophilic blocks constituted the shell and the hydrophobic blocks constituted the core. The size of the cationic colloids could be controlled in the range of 24 to 53 nm.