Poly-3-hydroxyhexanoate

Several types of bacterial polyesters that are produced by biosynthesis are poly-3-hydroxybutyrate, poly-4-hydroxybutyrate, poly-3-hydroxyvalerate, poly-3-hydroxyhexanoate, poly-3-hydroxy-heptanoate, etc., and their respective copolymer combinations. Due to their ability to degrade naturally in variety of environments, they will find a lot of applications in disposal items, short-term packaging, and also considered biocompatible in contact with living tissues and can be used for biomedical applications (e.g., drug encapsulation, tissue engineering) (Chauhan, 2012). 

Tiipathi, L., Wu, L.P., Chen, J. and Chen, G.Q. (2012) Synthesis of Diblock copolymer poly-3-hydroxybutyrate -block-poly-3-hydroxyhexanoate [PHB-b-PHHx] by a -oxidation weakened Pseudomonas putida KT2442. Microbial Cell Factories, 44,1-11. 

To date, various block copolymers have been produced using biological systems. This includes poly(3HB-fo-4HB) [17], P(3HB)-f>-poly(3-hydroxyvalerate-co-3-hydroxyheptanoate) [18], PHB-f -poly(hydroxyhexanoate) [19], poly 3HB-fc-poly(3-hydroxyheptanoate) [P(3HP)] [20], P(3HP)-f -poly(4-hydroxybutyrate) [P(4HB)] [21], poly(3-hydroxyhexanoate)-fe-poly(3-hydroxydecanoate)-co-[3-hydroxydodecanoate (3HDD)] [22] and poly[3-HDD-f -poly(3-hydroxy-9-decanoate)] [23]. These studies were motivated by the fact that although random copolymers, such as poly(3HB-co-3HV) and poly(3HB-co-4HB), exhibit useful mechanical and thermal properties they suffer from a deterioration of polymer properties due to the effect of ageing. It was found that all block copolymers exhibited improved properties compared with the two relative homopolymers, random and blend polymers. Various... 

Chen ZF, Cheng ST, Xu KT. Block Poly(ester-urethane)s based on poly(3-hydroxybu-tyrate-co-4-hydroxybutyrate) and poly(3-hydroxyhexanoate-co-3-hydroxyoctanoate). Biomaterials 2009 30(12) 2219-30. 

Polyhydroxyalkanoates (PHAs) are polyesters of hydroxyacids (HAs) with the general structural formula as depicted in Figure 1 Where X varies from 600 to 35,000 n = 1 R = hydrogen Poly (3-hydroxypropionate) R = methyl Poly (3-hydroxybutyrate) R = ethyl Poly (3-hydroxyvalerate) R = propyl Poly (3-hydroxyhexanoate) R = pentyl Poly (3-hydroxyoctanoate) R = nonyl Poly (3-hydroxydodecanoate) n = 2 R = hydrogen Poly (4-hydroxybutyrate) n = 3 R = hydrogen Poly (5-hydroxyvalerate) (Ojumu et al., 2004). 

R = (CH2)2CH3 Poly(3-hydroxyhexanoate) R = (CH2)4CH3 Poly(3-hydroxyoctanoate)... 

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