A surfactant-free emulsion RAFT polymerization of methyl methacrylate in a continuous tubular reactor

Abstract

In this work, a surfactant-free emulsion RAFT polymerization of methyl methacrylate (MMA) without any hydrophilic macro-RAFT agent was successfully carried out in a continuous tubular flow reactor with a mixed solvent of water and dimethyl formamide (DMF), which allowed the system to form an emulsion in situ, using 4-cyano-4-(thiobenzoylthio)pentanoic acid (CTBCOOH) as the chain transfer agent and emulsion stabilizer under the synergistic effect of sodium hydroxide (NaOH), and 2,2′-azobisisobutyronitrile (AIBN) as the initiator. The resulting latexes showed good stability and the polymerization demonstrated typical “living”/controlled characteristics of RAFT polymerization: first-order kinetics, linear increase of molecular weights with monomer conversion and narrow molecular weight distributions for the resulting PMMA. NMR spectroscopy and chain-extension experiments confirmed the attachment and livingness of the RAFT terminal group in the obtained polymer chain ends.