Peculiar spherulitic morphologies and melting behavior of block copolymer containing poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and poly(ɛ-caprolactone) units

Polyhydroxyalkanoates based copolymers

Polyhydroxyalkanoates (PHAs) belong to a family of natural polyesters and are produced under unbalanced growth conditions as intracellular carbon and energy reserves by a wide variety of microorganisms. Being biodegradable, biocompatible and environmental friendly thermoplastics, the PHAs are considered as future polymers to replace petrochemicals based plastics. In this review, the introduction section deals with the brief discussion on PHA nature, availability, raw materials for production, processing etc. This is followed by the discussions on modifications. The copolymer syntheses by bacterial and chemical methods have been discussed. Under chemical methods, unsaturated side chains and their derivatives, oligomer, coupling, macro-initiating, trans-esterification, radiation grafting, click chemistry, ring opening and several miscellaneous polymerization methods have been elaborated. A brief discussion on applications has been incorporated. The last section includes conclusion and future perspectives.

Poly(3-hydroxybutyrate) and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate): Structure, Property, and Fiber

Poly(3-hydroxybutyrate) [P(3HB)] and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] are produced by various microorganisms as an intracellular carbon and energy reserve from agricultural feedstocks such as sugars and plant oils under unbalanced growth conditions. P(3HB) and P(3HB-co-3HV) have attracted the attention of academia and industry because of its biodegradability, biocompatibility, thermoplasticity, and plastic-like properties. This review first introduced the isodimorphism, spherulites, and molecular interaction of P(3HB) and P(3HB-co-3HV). In addition, the effects of 3HV content on the melting temperature and crystallization rate were discussed. Then the drawbacks of P(3HB) and P(3HB-co-3HV) including brittleness, narrow melt processing window, low crystallization rate, slow biodegradation rate in body, and so on were summarized. At last, the preparation, structure, and properties of P(3HB) and P(3HB-co-3HV) fiber were introduced.