Enzyme-Catalyzed Polycondensation of Polyester Macrodiols with Divinyl Adipate: A Green Method for the Preparation of Thermoplastic Block Copolyesters

摘要

Enzyme-catalyzed polycondensation for the synthesis of block copolymers was reported for the first time. Thermoplastic block copolyesters containing poly[(R)-3-hydroxybutyrate] (PHB) and poly[(R)-3-hydroxyoctanoate] (PHO) blocks were enzymatically prepared by one-or two-step lipase-catalyzed polycondensation. Novozym 435-catalyzed reaction of PHB-diol (M_n of 3100 g/mol, GPC), PHO-diol (M_n of 3200 g/mol, GPC), and divinyl adipate gave block poly(HB-co-HO) (M_n of 9800 g/mol, GPC) with randomly arranged blocks in 55% yield. In two-step polycondensations, Novozym 435-catalyzed reaction of PHB-diol and divinyl adipate afforded 73% of PHB containing two vinyl ester end groups (M_n of 2700 g/mol, GPC), which was further reacted with PHO-diol in the presence of Novozym 435 to give block poly(HB-eo-HO)s (M_n of 8800-14 200 g/mol, GPC) with A-B-type arranged blocks in 55-62% yield. The enzymaticaliy prepared block copolyesters demonstrated T_m of 136- 142 °C and 142-153 °C and T_g of -37 to-39 °C and were potentially useful thermoplastic biodegradable and biocompatible materials.