Investigating the structure-property relationship of bacterial PHA block copolymers

Christopher W.J. McChalicher; Friedrich Srienc

doi:10.1016/j.jbiotec.2007.04.014

Investigating the structure-property relationship of bacterial PHA block copolymers

Christopher W.J. McChalicher, Friedrich Srienc

Biotechnology Institute

Research output: Contribution to journal › Article › peer-review

79 Scopus citations

Abstract

Mechanical testing of solvent cast films consisting of short-chain-length (SCL) polyhydroxyalkanoate (PHA) films suggested that films consisting of block copolymers retained more elasticity over time with respect to films of similar random copolymers of comparable composition. Two experimental techniques, wide angle X-ray scattering (WAXS) and uniaxial extension, were used to quantitatively investigate the structure-property relationship of bacterially synthesized PHA block copolymers of poly(3-hydroxybutyrate) (PHB) homopolymer and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) random copolymer (PHBV) segments. Uniaxial testing experiments yielded the Young's modulus, ultimate tensile strength, and the elongation until fracture of the films. Percent crystallinity was determined by deconvolution of amorphous and crystalline scattering peaks obtained from WAXS. Two PHBV films containing either 8% 3-hydroxyvalerate monomer (3HV) or 29% 3HV exhibited a quick transition to brittle behavior, decreasing to less than 20% percent elongation at fracture within a few days after annealing. Conversely, the block copolymer samples remained higher than 100% elongation at fracture a full 3 months after annealing. Because block copolymers covalently link polymers that would otherwise form thermodynamically separate phases, the rates and degrees of crystallization of the block copolymers are less than the random copolymer samples. These differences translate into materials that extend the property space of biologically synthesized SCL PHA.

Original language	English (US)
Pages (from-to)	296-302
Number of pages	7
Journal	Journal of Biotechnology
Volume	132
Issue number	3
DOIs	https://doi.org/10.1016/j.jbiotec.2007.04.014
State	Published - Nov 1 2007

Bibliographical note

Funding Information:
The authors would like to thank Jack Lewis, Professor of Orthopedic Surgery at the University of Minnesota, for the equipment used to complete the tensile testing trials. Portions of this work were completed at the Minnesota Characterization Facility, which receives partial support by the NSF through the NNIN program. This research was supported by the 3M Science and Technology Fellowship and by the University of Minnesota's Initiative for Renewable Energy and the Environment (IREE).

Copyright:
Copyright 2009 Elsevier B.V., All rights reserved.

Keywords

Block copolymers
Mechanical properties
Polyhydroxyalkanoates (PHA)

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10.1016/j.jbiotec.2007.04.014

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title = "Investigating the structure-property relationship of bacterial PHA block copolymers",

abstract = "Mechanical testing of solvent cast films consisting of short-chain-length (SCL) polyhydroxyalkanoate (PHA) films suggested that films consisting of block copolymers retained more elasticity over time with respect to films of similar random copolymers of comparable composition. Two experimental techniques, wide angle X-ray scattering (WAXS) and uniaxial extension, were used to quantitatively investigate the structure-property relationship of bacterially synthesized PHA block copolymers of poly(3-hydroxybutyrate) (PHB) homopolymer and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) random copolymer (PHBV) segments. Uniaxial testing experiments yielded the Young's modulus, ultimate tensile strength, and the elongation until fracture of the films. Percent crystallinity was determined by deconvolution of amorphous and crystalline scattering peaks obtained from WAXS. Two PHBV films containing either 8% 3-hydroxyvalerate monomer (3HV) or 29% 3HV exhibited a quick transition to brittle behavior, decreasing to less than 20% percent elongation at fracture within a few days after annealing. Conversely, the block copolymer samples remained higher than 100% elongation at fracture a full 3 months after annealing. Because block copolymers covalently link polymers that would otherwise form thermodynamically separate phases, the rates and degrees of crystallization of the block copolymers are less than the random copolymer samples. These differences translate into materials that extend the property space of biologically synthesized SCL PHA.",

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note = "Funding Information: The authors would like to thank Jack Lewis, Professor of Orthopedic Surgery at the University of Minnesota, for the equipment used to complete the tensile testing trials. Portions of this work were completed at the Minnesota Characterization Facility, which receives partial support by the NSF through the NNIN program. This research was supported by the 3M Science and Technology Fellowship and by the University of Minnesota's Initiative for Renewable Energy and the Environment (IREE). Copyright: Copyright 2009 Elsevier B.V., All rights reserved.",

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N2 - Mechanical testing of solvent cast films consisting of short-chain-length (SCL) polyhydroxyalkanoate (PHA) films suggested that films consisting of block copolymers retained more elasticity over time with respect to films of similar random copolymers of comparable composition. Two experimental techniques, wide angle X-ray scattering (WAXS) and uniaxial extension, were used to quantitatively investigate the structure-property relationship of bacterially synthesized PHA block copolymers of poly(3-hydroxybutyrate) (PHB) homopolymer and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) random copolymer (PHBV) segments. Uniaxial testing experiments yielded the Young's modulus, ultimate tensile strength, and the elongation until fracture of the films. Percent crystallinity was determined by deconvolution of amorphous and crystalline scattering peaks obtained from WAXS. Two PHBV films containing either 8% 3-hydroxyvalerate monomer (3HV) or 29% 3HV exhibited a quick transition to brittle behavior, decreasing to less than 20% percent elongation at fracture within a few days after annealing. Conversely, the block copolymer samples remained higher than 100% elongation at fracture a full 3 months after annealing. Because block copolymers covalently link polymers that would otherwise form thermodynamically separate phases, the rates and degrees of crystallization of the block copolymers are less than the random copolymer samples. These differences translate into materials that extend the property space of biologically synthesized SCL PHA.

AB - Mechanical testing of solvent cast films consisting of short-chain-length (SCL) polyhydroxyalkanoate (PHA) films suggested that films consisting of block copolymers retained more elasticity over time with respect to films of similar random copolymers of comparable composition. Two experimental techniques, wide angle X-ray scattering (WAXS) and uniaxial extension, were used to quantitatively investigate the structure-property relationship of bacterially synthesized PHA block copolymers of poly(3-hydroxybutyrate) (PHB) homopolymer and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) random copolymer (PHBV) segments. Uniaxial testing experiments yielded the Young's modulus, ultimate tensile strength, and the elongation until fracture of the films. Percent crystallinity was determined by deconvolution of amorphous and crystalline scattering peaks obtained from WAXS. Two PHBV films containing either 8% 3-hydroxyvalerate monomer (3HV) or 29% 3HV exhibited a quick transition to brittle behavior, decreasing to less than 20% percent elongation at fracture within a few days after annealing. Conversely, the block copolymer samples remained higher than 100% elongation at fracture a full 3 months after annealing. Because block copolymers covalently link polymers that would otherwise form thermodynamically separate phases, the rates and degrees of crystallization of the block copolymers are less than the random copolymer samples. These differences translate into materials that extend the property space of biologically synthesized SCL PHA.

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Investigating the structure-property relationship of bacterial PHA block copolymers

Abstract

Bibliographical note

Keywords

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