title: Enzyme-catalyzed polycondensation of polyester macrodiols with divinyl adipate: a green method for the preparation of thermoplastic block copolyesters.
abstract: 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-co-HO)s (M(n) of 8800-14 200 g/mol, GPC) with A-B-type arranged blocks in 55-62% yield. The enzymatically prepared block copolyesters demonstrated T(m) of 136-142 degrees C and 142-153 degrees C and T(g) of -37 to -39 degrees C and were potentially useful thermoplastic biodegradable and biocompatible materials.
authors.affiliation: Department of Chemical & Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore.
authors.forename: Shiyao
authors.initials: S
authors.lastname: Dai
authors.forename: Liang
authors.initials: L
authors.lastname: Xue
authors.forename: Manfred
authors.initials: M
authors.lastname: Zinn
authors.forename: Zhi
authors.initials: Z
authors.lastname: Li
mesh_terms: D000272:Adipates / Q000737:chemistry / Q000378:metabolism*; D002384:Catalysis; D004800:Enzymes, Immobilized; D005656:Fungal Proteins; D006358:Hot Temperature; D006885:Hydroxybutyrates / Q000737:chemistry / Q000378:metabolism*; D008049:Lipase / Q000737:chemistry / Q000378:metabolism*; D011091:Polyesters / Q000737:chemistry / Q000378:metabolism*; D000094122:Polyhydroxybutyrates
chemical_list: D000272:Adipates; D004800:Enzymes, Immobilized; D005656:Fungal Proteins; D006885:Hydroxybutyrates; D008049:Lipase; D011091:Polyesters; C476611:poly(3-hydroxybutyrate-co-3-hydroxyoctanoate); D000094122:Polyhydroxybutyrates; C088151:poly(3-hydroxyoctanoic acid); C003182:poly-beta-hydroxybutyrate; C472390:divinyl adipate; C093667:Novozyme 435