MONTE-CARLO SIMULATION OF THE CYCLIZATION CHAIN EXTENSION KINETICS FOR THE CATIONIC POLYMERIZATION OF HEXAMETHYLCYCLOTRISILOXANE

A Monte Carlo method has been used to simulate the kinetic dependencies related to ring-chain competition in the cationic polymerization of hexamethylcyclotrisiloxane. Several variants of mechanisms of this polymerization were considered. Good agreement between computational and experimental results was obtained for the dual mechanism comprising the direct stepwise addition of monomer to the growing chain end in competition with intra- and intermolecular condensation reactions. The additional assumption was made that the monomer molecule assists in the condensation. It was also shown that the experimental observations may conform to a pure acidolytic condensation pathway, assuming that shorter chains preferentially enter the intermolecular condensation and that the condensation is subjected to the intra-inter catalysis.