Green polymer chemistry: lipase-catalyzed synthesis of bio-based reactive polyesters employing itaconic anhydride as a renewable monomer

Itaconic acid is a platform compound for bio-based renewable materials. This study employs itaconic anhydride (IAn) as a novel monomer for lipase-catalyzed ring-opening addition condensation polymerization (ROACP) involving dehydration to produce reactive polyesters. ROACP reactions were conducted by combining a cyclic anhydride and a diol. IAn, succinic anhydride (SAn) and glutaric anhydride (GAn) were used as the cyclic anhydrides, and 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol and 1,10-decanediol were used as the diols. ROACP between two monomers, IAn and a diol, did not occur. Model reactions using IAn and n-octyl alcohol provided useful information about the regioselectivity and substrate selectivity of IAn. ROACP using three monomer components, IAn, SAn or GAn, and a diol, produced polyesters in good-to-high yields. From the SAn reactions, polyesters with M-n values of 650-3510 with 1.3-2.6 IAn units per molecule were obtained. From the GAn reactions, these values were 560-3690 and 1.2-3.1, respectively. The crosslinking reaction of a product polyester showed its reactive nature, giving a crosslinked hard solid polyester. The present polyesters derived from renewable starting materials have potential applications as macromonomers, telechelics, or crosslinking reagents, and the benign character of the ROACP reaction makes it appropriate for green polymer chemistry.