Candida antarctica lipase B catalyzed polymerization of lactones: Effects of immobilization matrices on polymerization kinetics & molecular weight

This study investigated the effect of enzyme immobilization on its activity for the ring-opening polymerizations of lactones with differing ring sizes. Candida antarctica lipase B (CALB) was immobilized on a wide array of support materials that varied in polymer composition, relative hydrophobicity, pore diameter, and surface area. The reaction rates and polymer molecular weights were monitored by in situ NMR measurements. Synchrotron infrared microspectroscopy (SIRMS) was used to study the enzyme distribution and secondary structure within the support matrix. The fastest reaction rates resulted by immobilization of CALB on the macroporous matrices QDM 2-3-4 and Accurel. Both of these are constructed from polypropylene and had CALB distributed throughout the matrix particles. Immobilized CALB on QDM 2-3-4 gave e-caprolactone (e-CL) conversion that reached 50 and 95% in 12 and 60 min, respectively. In comparison, by using CALB immobilized on Deloxan HAP, a 50% CL conversion required 120 h. Other changes th...