About Propagation Rate Constants in Carbocationic Polymerizations

摘要

Published carbocationic propagation rate constants vary between 2 10~3 and 5 10~9 L·mol~(-1)·s~(-1), e.g. for k_p~(+-) with styrene in CH_2Cl_2. The low values were deduced from an evaluation of [P_n~(+-)], the high values from competitive experiments assuming diffusion-controlled termination. Recent kinetic and spectrophotometric studies of indene living polymerization have given intermediate values (5 10~4 to 5 10~5 L·mol~(-1)·sec~(-1). An explanation of the high values obtained by the competition method is suggested.