title: Sequence distribution in microbial poly(3-hydroxybutyrate-co-3-hydroxyvalerate) co-polyesters determined by NMR and MS.
abstract: The microstructure of bacterial poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolyesters (PHBV) as well as a mixture of two PHBV copolyesters of different comonomer composition and sequence distribution was studied by 13C NMR based on dyad and triad analysis and multistage electrospray ionization mass spectrometry (ESI-MSn). Both techniques gave results that were in good agreement for all investigated samples. The effect of microstructure on PHBV thermal properties was investigated from the melting behavior of samples. A PHBV copolyester with randomly distributed hydroxyvalerate units (12.0 mol % HV) showed a single melting peak, whereas samples with nonrandom composition distribution showed multiple melting peaks in their thermograms. Such complex melting behavior suggested that the 12.9 and 27.1 mol % PHBV copolyesters were actually blends of several copolymers with widely different comonomer-unit composition.
authors.affiliation: National Institute of Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia. ema.zagar@ki.si
authors.forename: Ema
authors.initials: E
authors.lastname: Zagar
authors.forename: Andrej
authors.initials: A
authors.lastname: Krzan
authors.forename: Grazyna
authors.initials: G
authors.lastname: Adamus
authors.forename: Marek
authors.initials: M
authors.lastname: Kowalczuk
mesh_terms: D002152:Calorimetry, Differential Scanning; D020118:Cupriavidus necator / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D011091:Polyesters / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013696:Temperature
chemical_list: D011091:Polyesters