Facile Synthesis of Soap-Free Latexes of Methacrylic Copolymers via Sulfur-Free Reversible Addition-Fragmentation Chain Transfer Emulsion Polymerization br

Conventional reversible addition-fragmentationchain transfer (RAFT) emulsion polymers contain sulfur residuesand low-molar-mass surfactants that contribute to undesired odorand deleterious effects offinal materials. Herein, we show how livingpolymer chains obtained by catalytic chain transfer polymerization ofsurface-active monomers allyloxy polyoxyethylene(10)nonyl ammo-nium sulfate and methyl methacrylate can be used as an efficientstabilizer in sulfur-free RAFT (SF-RAFT) emulsion polymerization,resulting in soap-free latexes. The reactive surfactant concentrationcould decrease to 0.8 wt % in thefinal emulsion; meanwhile, theresultant latexes show good colloidal stability with an average particlesize ranging from 110 to 135 nm. Furthermore, semibatch SF-RAFTemulsion polymerization results in a well-controlled polymerizationprocess, as evidenced by the smooth increase in molecular weight ofpolymer chains as the polymerization progressed. It is also apparent from the chain extension experiments that the SF-RAFTemulsion polymerization of methacrylic monomers exhibits a living characteristic