Emulsifier‐Free, Organotellurium‐Mediated Living Radical Emulsion Polymerization of Styrene

Summary: Emulsifier‐free organotellurium‐mediated living radical emulsion polymerization (emulsion TERP) of styrene was successfully carried out using a water‐soluble TERP agent, poly(methacrylic acid)‐methyltellanyl (PMAA30‐TeMe) (degree of polymerization of PMAA, 30) and a water‐soluble thermal initiator, 4,4′‐azobis(4‐cyanovaleric acid) (V‐501), which were neutralized with NaOH, at 60 °C with stirring at 220 rpm, where most of monomer floated as a layer onto an aqueous medium. The polymerization proceeded without an induction period and completed within 20 h, resulting in a stable PS emulsion without any coagulation, although the particle size distribution was bimodal. The polymerization livingness was maintained, although the experimental number‐average molecular weight (Mn) differed from theoretical Mn, and polydispersity (Mw/Mn) reached a slightly high value (2.1) at the completion of the polymerization.