LIPASE-CATALYZED RING-OPENING POLYMERIZATION OF LACTONES - A NOVEL ROUTE TO POLY(HYDROXYALKANOATE)S

Lipases from porcine pancreas and from Pseudomonas cepacia catalyze th e ring-opening polymerization of lactones. Polymerization of the four- membered beta-butyrolactone yielded poly(3-hydroxybutyrate) in up to 8 9% yield with a degree of polymerization of 3-12. Polymerization of th e four-membered beta-propiolactone, the five-membered gamma-butyrolact one, and the seven-membered epsilon-caprolactone also yielded the corr esponding polyesters in good yields with degrees of polymerization up to 25. Coordination catalysts, such as alumoxanes, fail in the homopol ymerization of gamma-butyrolactone; thus this lipase route ill the fir st homopolymerization of gamma-butyrolactone. To characterize the prod uct polyesters, we used the method of MALDI-TOF mass spectroscopy to d etermine both the true molecular weight of the components and the mass of the repeat unit.