title: Comonomer compositional distribution and thermal and morphological characteristics of bacterial poly(3-hydroxybutyrate-co-3-hydroxyvalerate)s with high 3-hydroxyvalerate content.
abstract: The comonomer compositional distribution and thermal and morphological characteristics were investigated for five bacterially synthesized poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] samples with 3HV content of 45, 49, 70, 80, and 96 mol %. All these samples were fractionated into many fractions with widely different 3HV content by changing solvent/nonsolvent volume ratio of chloroform/n-heptane mixtures. Bacterial P(3HB-co-3HV) samples investigated in this study were found to have broad comonomer compositional distribution. The tendencies of the fractional precipitation of the P((3HB-co-3HV)s with 3HV content lower than 60 mol % and those with 3HV higher than 80 mol % were found to be contrary. The 3HV content dependences of the thermal properties and crystalline structures were investigated for bacterial poly(3-hydroxybutyrate) [P(3HB)] and a series of compositionally well-fractionated P(3HB-co-3HV) samples with 3HV content ranged from 14 to 98 mol % by DSC, WAXD, and solid-state (13)C NMR. It was found that P(3HB-co-3HV) samples with 3HV content lower than about 47 mol % form the crystalline lattice having the P(3HB) homopolymer type lattice including the 3HV unit as the crystal constituent, and those with a 3HV content higher than about 52 mol % form the crystalline lattice having the P(3HV) homopolymer type lattice including the 3HB units. Thus, P(3HB-co-3HV)s show the crystalline structural change in a very narrow range of 3HV content.
authors.affiliation: Department of Biomolecular Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8501, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: S
authors.initials: S
authors.lastname: Yamada
authors.forename: N
authors.initials: N
authors.lastname: Asakawa
authors.forename: T
authors.initials: T
authors.lastname: Yamane
authors.forename: N
authors.initials: N
authors.lastname: Yoshie
authors.forename: Y
authors.initials: Y
authors.lastname: Inoue
mesh_terms: D001673:Biodegradation, Environmental; D002152:Calorimetry, Differential Scanning; D005591:Chemical Fractionation; D003460:Crystallization; D020118:Cupriavidus necator / Q000378:metabolism*; D005285:Fermentation; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D011091:Polyesters / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D014961:X-Ray Diffraction; D000094122:Polyhydroxybutyrates
chemical_list: D011091:Polyesters; C052620:poly(3-hydroxybutyrate)-co-(3-hydroxyvalerate); D000094122:Polyhydroxybutyrates