Enzymatic synthesis of polycaprolactone: Effect of immobilization mechanism of calb on polycaprolactone synthesis

Surface-modified rice husk ash was used as an inorganic support material for immobilization of Candida antarctica lipase B. (3-aminopropyl) trimethoxysilane was used for surface modification. Immobilization of CALB was performed via both physical adsorption and cross-linking. PCL synthesis was carried out by using these immobilized enzymes, free enzyme and Novozyme 435®. Molecular weight distribution of polymer samples was obtained by gel permeation chromatography (GPC) and chain structures of the polymer samples were observed by hydrogen nuclear magnetic resonance (¹H-NMR). The highest monomer conversion is generally obtained by using cross-linked enzyme, around 90%. PDI values for all polymer samples were approximately 1.5 which can be considered as acceptable. In general cross-linked enzymes were better than physically adsorbed enzymes in terms of average molecular weights. It can be concluded that PCL can be synthesized with these immobilized enzymes with high molecular weight and low PDI values.