THE HYDROLYTIC POLYMERIZATION OF EPSILON-CAPROLACTONE BY TRIPHENYLTIN ACETATE

The polymerization of ε-caprolactone (CL) using triphenyltin acetate has been investigated. Polymers with broad MWD were obtained in almost quantitative yield. After an initial induction period, the polymerization showed zero order kinetics with respect to monomer and nearly first order with respect to catalyst. The mechanism of the propagation reaction is proposed to proceed via an ester alcoholysis, with initiation by traces of water. The zero order kinetics are explained as follows: the tin catalyst is coordinated by the cyclic lactone, monomer addition to the polymer chain in the rate-determining step results in formation of an acyclic ester link, which is no longer a strong donor, and leads to a coordinatively unsaturated tin species. © 1990 Springer-Verlag.