Solid state properties of poly-β-hydroxybutyrate and of its oligomers

Abstract

. Can. J. Chem. 59,38 (1981).The solid state properties of poly-0-hydroxybutyrate (PHB) were investigated for samples with degrees of polymerization (m) from 4 to 994. The observed melting points ranged from 47°C to 18O0C. Electron diffractograms on carefully prepared single crystals of a high molecular weight sample provided data which confirmed the reported a and b parameters from X-ray fiber diffraction and provided clear justification for the P2,2,2, space group. The observed intensities in the electron diffractogram, corresponding to (hM) reflections, were compared with the predicted intensities for two proposed structures in the literature. The observed and calculated structure factors for both structures were in good agreement. Small angle X-ray diffraction ofthe meridional maximum for annealed "cold drawn" and "hot drawn" fibers showed a distinctly different dependence on temperature than the maximumm stacks of lamellar single crystals. For oligomers a long spacing was observed which was about twice the length of the sample DPn multiplied by the crystalline advance per monomer. Les points de fusion vont de 47°C a 180°C. Les absences systematiques observees en diffraction electronique sur monocristaux de forte masse confirment le groupe spatiale P2,2,2, propose a partir du diagramme a fibre (rayons-X). Les intensites observies des reflections (hkO) du cliche de diffraction tlectronique sont en accord avec celles predites a partir de deux structures crystallines proposies dans la literature et basies sur les donnees du diagramme a fibre. La diffusion meridionale des rayons-X aux petlts angles pour des fibres ttirtes "ifroid" et "achaud" a e t t enregistree et la variation des maximade diffusion, enfonction de la temperature, differe sensiblement de ce qui est observe pour la variation de l'kpaisseur de lamelles monocristallines. Pour des oligomtres cristallins I'observation d'une tache de diffraction dont I'espacement est deux fois la longueur de la chaine dans sa conformation crystalline mtne proposer une maille avec deux chaines bout bout selon I'axe c.

Hydrolytic degradation of isolated poly(β-hydroxybutyrate) granules

“…25 for oligomers of PHB show that the same trend is followed (decrease in Tm with decrease in DP), although the Tm they measured were better defined due to the fractionation they performed on their samples to obtain ｮ ｡ ｲ ｲ ｯ ｷ ｾ ｣ ｵ ｴ oligomer aliquots.…”

Pyrolysis of bacterial polyalkanoates

“…This chiral polymer occurs as spherical hydrophobic granules in the cells of a wide variety of bacteria (5) and is easily harvested by a simple cell rupture (6,7). The solid state structure of this polymer has been studied intensively (8)(9)(10)(11). Because of its P-hydroxyalkanoate structure, PHB and its related family of poly-Phydroxyalkanoates (PHA) are thermally unstable (12) and have potential as a source of small molecule organic chemicals rather than as thermoplastics (cf.…”

“…J. Chem. 59,2306(1981. Pyrolysis products from bacterial polyesters, poly-P-hydroxybutyrate (PHB), and froma heteropolyester(P-hydroxyvalerate and P-hydroxybutyrate) were identified.…”

“…J. Chem. 59,2306(1981. On a identifie les produits provenant de la pyrolyse des polyesters bactiriens poly-P-hydroxybutyrate (PHB) et du polyester heterogene (P-hydroxyvalirate e t P-hydroxybutyrate).…”

Exploring biodegradable polymer production from marine microbes

“…The single crystals with well defined structure are the monolamellar form that are reported to be forming in different solvent conditions like chloroform/ethanol, propylene carbonate, poly(ethylene glycol), and so forth [167][168][169][170] which were investigated by microscopic analysis to study the surface morphologies and crystal structure. The thickness is dependent on many factors such as molecular weight, solvent, and crystallization temperature.…”