Schiff base aluminum catalysts containing morpholinomethyl groups in the ring opening polymerization of rac-lactide

A series of Schiff base aluminum(III) complexes bearing morpholinomethyl substituents were synthesized. Comprehensive investigations on their stereoselective and kinetic features in the ring opening polymerization of lactide were carried out. The ring opening polymerization proved to be first-order in the catalyst and the monomer. Linear relationships between the numberaverage molecular weight of the polylactide and the monomer conversion were consistent with a well-controlled polymerization. The propagation rate was strongly affected by morpholinomethyl substituents on the salicylaldehyde moiety.