Chain-transfer-dependent termination in emulsion polymerization

The influence of chain transfer agent, tert-dodecyl mercaptan, on the kinet ics of semi-batch seeded emulsion (co)polymerizations has been studied. Due to the very low water-solubility of tert-dodecyl mercaptan, the radical re sulting after transfer to this chain transfer agent is not likely to exit t he growing polymer particles and the kinetics should not be affected by thi s radical loss route. This has been confirmed experimentally for styrene-bu tadiene and butyl acrylate systems. However, increasing the level of tert-d odecyl mercaptan at large (final) particle sizes for styrene-butadiene led to a reduced rate of polymerization. This only can be attributed to an incr eased rate of termination.