Highly efficient enzymatic catalysis for cyclocarbonate polymerization

Abstract

In this study, we developed a metal-free biosynthetic strategy of enzymatic polymerization to fabricate aliphatic poly(pentamethylene carbonate) (PPMC). Novozym-435 lipase showed considerably high catalytic efficiency, and high molecular weights (Mn) of up to 6.0 × 104 g mol−1 were readily achieved through the ring-opening polymerization of cyclobis(pentamethylene carbonate). The reaction parameters, including monomer concentration and lipase concentration, were examined. It seemed that little polymer degradation occurred during the polymerization, which would happen in the case of organometallic catalysis. In vitro enzymatic degradation tests indicate that the carbonate groups may not be sensitive to catalysis from the lipases of porcine pancreas and Candida rugosa (AYS). PPMC was found to possess higher flexibility and tenacity, relative to poly(trimethylene carbonate). Thermogravimetrical analyses suggest that the chemical structure of poly(alkylene carbonate)s exerts a significant influence on their thermal stability and decomposition mechanism. PPMC with a high Mn of up to 6.0 × 104 g mol−1 can be readily afforded under the catalysis of an immobilized lipase from Candida antarctica (Novozym-435). The result sounds attractive, as presently the low catalytic efficiency is known as the main restriction for the industrialization of enzyme catalysis.