MONTE-CARLO SIMULATION OF KINETICS AND CHAIN-LENGTH DISTRIBUTIONS IN LIVING FREE-RADICAL POLYMERIZATION

The kinetics and chain length distributions occurring in living free-r adical polymerizations are simulated using a hybrid Monte Carlo algori thm. The new algorithm is much faster than the conventional one becaus e the activation/deactivation exchange reactions, which are CPU intens ive, are treated by a biased-sampling method with an analytical expres sion for the exchange equilibrium, while the reactions of chain propag ation, irreversible chain termination, etc. are treated by exact stoch astic Monte Carlo simulation, Two models of living radical polymerizat ions, i.e., the polymerization initiated by alkoxyamines and the nitro xide radical, 2,2,6,6-tetramethyl-1-piperidinyloxy, mediated radical p olymerization, are simulated to study the effects of experimental vari ables, such as the concentration ratio of stable free radicals to init iators, initiation rate constants, etc., on the kinetics and molecular weight distributions. A comparison between simulated and analytical r esults in the literature is made. Taking thermal. initiation into cons ideration, the algorithm reproduces the experimental results very well . Therefore, its feasibility and usefulness in studying living free-ra dical polymerization are demonstrated.