Dynamics of Lipase Catalyzed Enzymatic Degradation of Poly(bisphenol-A carbonate)

Poly(bisphenol-A carbonate) (PC) was degraded in solution at various temperatures $(26-70^ \circ C)$ by different lipases, Candida Rugosa (CR), Hog Pancreas (HP), Lipolase (LL), and Novozyme (NV), in various solvents. The degradation of PC was monitored using gel permeation chromatography (GPC). The molecular weights of oligomers obtained were around \sim 1,400 irrespective of the lipases used. Continuous distribution kinetics was proposed to determine the rate coefficients of the polymers and deactivation of the enzyme. The FTIR analysis of the polymer before and after degradation showed that there is large reduction of carbonate linkages and generation of hydroxyl and acidic groups in the broken chains. The optimal temperatures for HP and other lipases were 50 and $60^ \circ C$, respectively. HP showed higher degradation activity at lower temperatures and the overall degradability of the lipases was in the order of LL > CR > NV > HP. The effect of viscosity and polarity of the solvents on the degradation of the polycarbonate was also investigated. While the degradation rate decreased with viscosity, it increased with polarity for the solvents