X-Ray Structure of Poly-β-hydroxybutyrate

Okamura, Keizo; Marchessault, R. H.

doi:10.1016/b978-1-4832-2843-3.50023-6

Cited by 76 publications

(38 citation statements)

References 8 publications

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“…Of particular interest in recent years have been polyesters with side groups attached to the main chain such. as poly-fl-h.ydroxybutyrate (Okamura & Marchessault, 1967) which occurs as an optically active natural polymer and polypivalolactone (Knobloch & Statton, 1967) which is an interesting synthetic fiber material.…”

Section: Introductionmentioning

confidence: 99%

Crystal structure of poly-ε-caprolactone

Bittiger¹,

Marchessault²,

Niegisch³

1970

Acta Crystallogr B Struct Crystallogr Cryst Chem

316

279

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The unit cell of poly-e-caprolactone was found to be orthorhombic with dimensions a = 7.496 + 0.002, b=4.974+0"001, c= 17.297+0-023/~ (fiber axis). The space group is P212121. This unit cell is only compatible with an extended planar chain conformation of the molecule involving two monomer residues related by a twofold screw axis in the chain direction. The P212~2~ space group and the density of 1.146 g.cm-3 indicate that the unit cell contains two chains with opposite orientation ('up' and 'down'). Intensity measurements and structure factor calculations require the rotation of the plane of the chains about their axis to an angle of 28 ° with respect to the a axis; longitudinal chain shift places the ester groups in planes perpendicular to the c axis. Folded chain single crystals with a lancet-like structure were observed by electron microscopy.

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Section: Introductionmentioning

confidence: 99%

Crystal structure of poly-ε-caprolactone

Bittiger¹,

Marchessault²,

Niegisch³

1970

Acta Crystallogr B Struct Crystallogr Cryst Chem

316

279

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“…The crystal structure of PHB is a orthorhombic form with unit cell parameters a = 0.576 nm, b = 1.320 nm, and c(fiber axis) = 0.596 nm, and space group P2 1 2 1 2 1 (Alper et al 1963;Okamura and Marchessault 1967). The conformational analysis by intermolecular energy calculation has indicated that the PHB molecule has a left-handed 2 1 helix conformation (Cornibert and Marchessault 1972;Yokouchi et al 1973;Bruckner et al 1988).…”

Section: Structure and Degradation Of Phb And Copolymersmentioning

confidence: 97%

Degradation of Natural and Artificial Poly[(R)-3-hydroxyalkanoate]s: From Biodegradation to Hydrolysis

Guérin

Renard

Langlois

2009

Microbiology Monographs

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Biodegradability of polymers has drawn much attention as a solution to problems concerning the global environment and biomedical technologies. Poly[(R)-3-hydroxybutyrate] and its copolymers are representative biodegradable polyesters which can be degraded in natural environments such as soil, sludge, freshwater, and seawater where many microorganisms utilize the degraded products as a carbon source. The ability to degrade poly[(R)-3-hydroxyalkanoate]s (PHAs) is widely distributed among fungi and bacteria and depends on the extracellular PHA depolymerases, which are carboxyesterases, and on the physical state of the polymer (amorphous or crystalline). Intracellular depolymerase systems lead to CO 2 and H 2 O when bacteria need energy or carbon sources. All polyesters are susceptible degradation by simple hydrolysis to some extent. The degradation rate is very dependent on the chemical structure and the crystallinity of the materials.

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“…In these strong fibers, there are two kinds of molecular and crystal structures: an a-structure with a 2/1 helix molecular conformation and a b-structure with a planar zigzag one (Okamura and Marchessault 1967;Yokouchi et al 1973;Orts et al 1990). The generation mechanism and the distribution of both structures are revealed by microbeam X-ray diffraction, and 3D analysis of fibers was performed to observe the inner structure of fibers without pretreatment or damage in a synchrotron radiation facility (SPring-8), Japan.…”

Section: Isothermal Crystallization In Ice Water Annealingmentioning

confidence: 98%

“…2c includes reflections simultaneously from both the a-structure (2/1 helix conformation; Okamura and Marchessault 1967;Yokouchi et al 1973) and the b-structure (planar zigzag conformation; Orts et al 1990) of P(3HB) that are drawn in Fig. 3.…”

Section: Structure Analysismentioning

confidence: 99%

Manufacturing of PHA as Fibers

Iwata

Tanaka

2009

Microbiology Monographs

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Poly[(R)-3-hydroxybutyrate] and its copolymers have not been recognized as practical because of its stiffness and brittleness. Recently, we succeeded in obtaining strong fibers by two kinds of new drawing techniques from microbial polyesters produced by both wild-type and recombinant bacteria. The improvement of the mechanical properties of fibers is due not only to the orientation of the molecular chains but is also due to the generation of a planar zigzag conformation. The highly ordered and inner structures of strong fibers with tensile strength of over 1.0 GPa were analyzed by microbeam X-ray diffraction and X-ray microtomography

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X-Ray Structure of Poly-β-hydroxybutyrate

Cited by 76 publications

References 8 publications

Crystal structure of poly-ε-caprolactone

Crystal structure of poly-ε-caprolactone

Degradation of Natural and Artificial Poly[(R)-3-hydroxyalkanoate]s: From Biodegradation to Hydrolysis

Manufacturing of PHA as Fibers

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