Cadmium acetate as a ring opening polymerization catalyst for the polymerization of rac-lactide, ε-caprolactone and as a precatalyst for the polymerization of ethylene

Abstract

In the present study, we have discussed the bulk ring opening polymerization (ROP) of rac-lactide (rac-LA) and e-caprolactone (e-CL) using Cd(OAc)2. Cd(OAc)2 appeared to be a good catalyst for the polymerization of rac-LA and e-CL yielding high molecular weight (Mn) polymers with narrow molecular weight distributions (MWDs). The catalytic activity of the system can be increased markedly upon using catalytic amount of BnOH as external alcoholic initiator. There is a first order dependence of the rate constant with respect to monomer concentrations as understood from the kinetic studies. The rate was found to be faster in the presence of BnOH. The polymerization process was controlled. The polymerization proceeded via the coordination-insertion mechanism without BnOH as well as activated monomer mechanism in the presence of BnOH. In the absence of BnOH, the acetyl group initiated the polymerization as understood from the 1H NMR and MALDI-TOF analysis. The benzyloxy group initiated the polymerization in the presence of BnOH. Moderate activity towards the polymerization of ethylene was observed using MAO as alkyl aluminum activator. The polymerization parameters towards the polymerization of ethylene were widely investigated.