Synthesis of acid-functional asymmetric aliphatic polyesters

Asymmetric telechelic polyesters were investigated by the use of functional initiators. Aluminum isopropoxide is a well known initiator for the living ring opening polymerization of aliphatic polyesters. The polymerization involves the selective acyl-oxygen bond cleavage of the cyclic monomer followed by a coordination-insertion polymerization mechanism. Asymmetric acid-functional poly(caprolactone) was synthesized using the same approach. The use of benzyl alcohol to initiate the ring opening polymerization of poly(caprolactone) and the selective deprotection to yield the requisite asymmetric acid functionality are discussed.