Enzymatic Degradation of the Copolyester P(BS-<i>co</i>-DGS)

Abstract

Lipase Novozym 435 was used as catalyst to degrade P(BS-co-DGS), which was a kind of PBS-based copolyester modified with diethylene glycol (DEG), in a THF/toluene mixed solvent system. P(BS-co-DGS) copolyesters were synthesized by copolymerization and characterized by 1H NMR. GPC and TGA were used to investigate average molecular weight and thermal property before and after degradation, respectively. After degraded by N435 for 30 h, the Mn of P(BS-co-DGS)10 (DEG content 10%) decreased from 8.33×104 to 3.52×104 g·mol-1 with some yellow oil droplets of oligomers appearing. And the initial decomposition temperature (the temperature at 5% mass loss) of P(BS-co-DGS)10 changed from 300.6 to 178.9. MALDI-TOF-MS results showed that none of DEG oligomers appeared in P(BS-co-DGS)10 degradation products. However, when the DEG content increased to 20%, there were the DEG circle oligomers as well as linear oligomers in the degradation products.