A systematic kinetic study in reversible Chain transfer catalyzed polymerizations (RTCPs) with germanium, tin, phosphorus, and nitrogen catalysts

This paper reports a systematic kinetic study on the reversible activation processes and polymerization rates in the reversible chain transfer catalyzed living radical polymerizations (RTCPs) of styrene (St) and methyl methacrylate with germanium (Ge), tin (Sn), phosphorus (P), and nitrogen (N) catalysts. The pseudo-first-order activation rate constant k_act significantly depended on monomers and the elements and substituents of the catalysts. For the St polymerization at 80 °C, k_act increased in the order of PI₃ (P catalyst) < p-tolyl germanium triiodide (tolyl- GeI ₃) (Ge catalyst) < N-iodosuccinimide (NIS) (N catalyst) < SnI₄ (Sn catalyst) < GeI₄ (Ge catalyst) at the same catalyst concentration. The polymerization rate was somewhat retarded in the studied systems due to the cross-termination between the propagating radical and the catalyst radical in situ formed in the polymerization.