Comments on the Paper 'Living Radical Polymerization: Kinetic Results'

摘要

It has heen reported that the rate of styrene bulk polymerization in the presenceof various adducts of di-t-butyl nitroxides does not depend on the initial concentration of the adduct. The reported rate is very similar to thermal self initiated polymerization of styrene at the same temperature. Therefore, it is proposed that thermal initiation controls the kinetics of nitroxidemediated polymerization. The adduct, on the other hand, participates in either bimolecular or unimolecular exchange reactions providing control over molecular weights and polydispersities in this system. This proposal is supported by the results of computer simulations of a bulk styrene polymerization in a system with unimolecular exchange. It was determined that the equilibrium constant equals K=(k sub a)/(k sub d) < or = 1X10(exp-12) mol/L(-1) and the deactivation rate constant is approximately k sub d approx.=1X10(exp 9) L/mol/s in the bulk polymerization of styrene in the presence of di-t-butyl nitroxides at 90 C.