Poly-3-hydroxyvalerate PHV

Shen X-W, Yang Y, Jian J, Wu Q, Chen G-Q (2009) Production and characterization of homopolymer poly(3-hydroxyvalerate) (PHV) accumulated by wild type and recombinant Aeromonas hydrophila strain 4AK4. Bioresour Technol 100 4296-4299 Shenoy SL, Bates WD, Frisch HL, Wnek G (2005a) Role of chain entanglements on fiber formation during electrospinning of polymer solutions good solvent, non-specific polymer-polymer interaction limit. Polymer 46 3372-3384... 

For example, natural biopolymers have been developed for use in the manufacturing of plastic containers. Poly-(hydroxyalkanoates) such as poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxyvalerate) (PHV) are naturally occurring polyesters produced by certain bacteria. 

The major commercial microial polyesters are polyhydroxyalkanoates (PHAs) (see Poly(3-HYDROXYALKANOATES)) Poly(3-hydroxybutyrate) (PHB) (8) is brittle, but as the number of carbon atoms in the side chains of PHAs increases, eg, poly(3-hydrox5Tvalerate) (PHV) (9), the properties tend from polypropylene-like to elastomeric. Copolymers, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), have a range of properties depending on composition (Table 1). 

The copolymer poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB-co-PHV) produced by A eutrophus has generated more interest than poly-(R)-3-hydroxybutyrate (PHB) homopolymer. Since these bacterial polyesters are biodegradable thermoplastics, their mechanical and physical properties have received much attention. PHB is a relatively stiff and brittle material because of its high crystallinity. However, the physiochemi-cal and mechanical properties of [P(HB-HV)] vary widely and depend on the molar percentage of 3-hydroxyvalerate (HV) in the copolymer (4,5) as shown inTable 1. Propionic acid is converted by a synthetase to propionyl-CoA, and the biosynthetic P-ketothiolase catalyzes the condensation of propionyl-CoA with acetyl-CoA to 3-ketovaleryl-CoA by the acetoacetyl-CoA reductase. The hydroxyvaleryl moiety is finally covalently linked to the polyester by the PHA synthase (6). 

Pearce, R. P. and Marchessault, R. H. Melting and CrystalUzation in Bacterial Poly(/ -hydroxyvalerate), PHV, and Blends with Poly(/3-hydroxybutyrate-co-hydroxyvalerate). Macromolecules. 27 3869-3874 (1994). 

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