Abstract:

Porcine pancreas lipase(PPL) immobilized on narrow distributed micron glass beads was employed successfully for ring-opening polymerization of ε-caprolactone(CL). Different polymerization conditions such as enzyme concentration, reaction temperature and reaction time were studied. The results showed that Mn of the resulting PCL was significantly increased compared with that catalyzed by PPL. Higher temperature and longer reaction time both contributed to gaining PCL with a higher molecular weight, while the yield had almost no change. In addition, for evaluating the recyclibilty of immobilized PPL on narrow distributed micron glass beads for the ring-opening polymerization of CL, we adopted the most severe reaction conditions(180 ℃, 240 h) in the recycling experiments. It was found that the recovered immobilized PPL could be used again with a compatible high catalytic activity. The highest Mn of 21300 of PCL could be obtained at a mass fraction of 5.18% of the reused immobilized PPL at 180 ℃ for 240 h, which is the highest Mn of PCL catalyzed by PPL. The excellent recyclability of immobilized PPL on narrow distributed micron glass beads is very helpful to its further industry applications.

Key words: Porcine pancreas lipase; Immobilization; Micron glass beads; Enzymatic ring-opening polymerization; Poly(ε-caprolactone)