Enzymatic ring opening polymerization of ε-caprolactone by using a novel immobilized biocatalyst

In this study, an amorphous silica material was used as a carrier to immobilize Candida antarctica lipase B (CALB) by crosslinking method for ring opening polymerization of ε-caprolactone (ε-CL). The optimum temperature, enzyme concentration and time period were investigated for poly(ε-caprolactone) (PCL) synthesis via ring opening polymerization of ε-CL catalyzed by immobilized CALB (IMCALB). Molecular weights of PCLs were determined by using gel permeation chromatography (GPC) and hydrogen nuclear magnetic resonance (1H-NMR) analysis. The surface morphologies of PCLs were analyzed by scanning electron microscopy (SEM). Besides, PCLs were successfully characterized by fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis. The results showed that the immobilized lipase by crosslinking method via glutaraldehyde possessed good activity and stability. By using this immobilized enzyme, high molecular weights and monomer conversions of PCLs were achieved about 9000 g/mol and 90%, respectively. This work has showed that activity of CALB increased about 17% dramatically after immobilization process, and PCL was synthesized via enzymatic polymerization catalyzed this novel enzyme, which provides an effective method for conducting "green polymer chemistry".