Polymerization of hexamethylcyclotrisiloxane with a biscatecholsiliconate. II. Kinetics of polymerization

The kinetics of polymerization were investigated for the polymerization of hexamethylcyclotrisiloxane (D3) in toluene with methanol or water as an initiator, benzyltrimethylammonium bis(o‐phenylenedioxy)phenylsiliconate as a catalyst, and dimethyl sulfoxide (DMSO) as a promoter. The rate of initiation was found to be comparable with both water and methanol. Addition of catechol drastically reduces the rate of initiation. The rate of propagation was found to be dependent upon the catalyst, DMSO, catechol and the aging of the catalyst solution. Two types of functional groups were postulated to be present during the propagation reaction, i.e., SiOH (dormant form) and SiONR4 (living form). The former can be converted to the latter by R4NOH derived from hydrolysis of catalyst. A postulated mechanism of polymerization with biscatecholsiliconate is presented.