Toward Well-Controlled ab Initio RAFT Emulsion Polymerization of Styrene Mediated by 2-(((Dodecylsulfanyl)carbonothioyl)sulfanyl)propanoic Acid

Reversible addition−fragmentation chain transfer (RAFT) ab initio emulsion polymerization of styrene mediated by 2-(((dodecylsulfanyl) carbonothioyl) sulfanyl) propanoic acid was investigated with sodium dodecyl sulfate (SDS), poly(acrylic acid)29-b-polystyrene5 trithiocarbonate macro-RAFT agent (PAA29-PSt5-RAFT), and poly(acrylic acid)29-b-polystyrene5 diblock co-oligomer (PAA29-PSt5) as the surfactant, respectively. Polystyrene latex having controlled molecular weight, relatively low PD and narrow particle size distribution was obtained by postneutralizing PAA29-PSt5-RAFT and PAA29-PSt5. This result was in agreement with the superswelling hypothesis that superswollen oligomer-containing particles caused the colloidal instability in the early stage of RAFT emulsion polymerization with SDS as surfactant. The successes of PAA29-PSt5-RAFT and PAA29-PSt5 were due to the high interfacial tensions of the styrene/water/surfactant systems that suppressed the superswelling and thus improved the colloidal instability. A majority of the initial RAFT molecules appeared to be converted at a low monomer conversion due to the inhibition period.