Precision enzymatic polymerization to polyesters with lipase catalysts

Ring-opening polymerization of lactones with different ring-size has been achieved via lipase catalysis. Small-size (4-membered) and medium-size lactones (6- and 7-membered) as well as macrolides (12-, 13-, 16-, and 17-membered) were subjected to the lipase-catalyzed polymerization. The polymerization behaviors strongly depended on the lipase origin and the ring-size of the lactones. In using Pseudomonas family lipases as catalyst, the polymerization of macrolides showing much lower anionic polymerizability proceeded much faster than that of epsilon-caprolactone. The enzymatic polymerizability of the lactones was evaluated by Michaelis-Menten kinetics. V(max) increased as a function of the ring-size, whereas K(m) values were not so different with each other. The granular immobilized lipase derived from Candida antarctica showed the extremely efficient catalysis in the polymerization of epsilon-caprolactone. Single-step synthesis of methacryl- and omega-alkenyl-type polyester macromonomers was achieved by the lipase-catalyzed polymerization of 13-membered lactone in the presence of vinyl esters acting as terminator. Lipase also catalyzed a polycondensation of dicarboxylic acid and glycol in the aqueous medium, in which the dehydration took place in water.