High Performance Biodegradable Polymeric Composite Materials Based on Bacterially Synthesized Polyesters

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The purpose of this research project was developments of new biodegradable polymeric materials, which have high mechanical strength and controllable biodegradability, based on bacterially synthesized polyesters. The main four subjects and the results were as follows.1.Bacterial synthesis, solid-state structure and properties of copoly (hydroxyalkanoic acid) s. A series of copoly (hydroxyalkanoic acid) s, such as poly (3-hydroxybutyric acid-co-3-hydroxy-valeric acid) s, poly (3-hydroxybutyric acid-co-4-hydroxybutyric acid) s, poly (3-hydroxy-butyric acid-co-3-hydroxyhexanoic acid) s, have been bacterially synthesized and the dependences of their crystalline structures, thermal properties and biodegradabilities on their comonomer unit compositions have been investigated.2.Miscibility and properties of polyester/polysaccharide blends. New biodegradable polymer blends of bacterial polyesters and chitin and chitosan have been developed and their phase behavior and biodegradability have been investigated. Polyesters and chitin/chitosan were found to form miscible blends via hudrogen-bonding interaction.3.Enhancement of biogegradation of biodegradable polymers by regulating phase structure and dynamic property through polymer blending. It was found that enzymatic biodegradation of chemosynthesized atctic poly (3-hydroxy-butyric acid), which is hardly biodegradable in the pure state, was enhanced by blending with amorphous polymers, such as atactic-poly (lactic acid) with high glass transition temperature.4.Regulation of solid-state structure and improvement of physical properties of polyesters by introducing intermolecular hydrogen-bonds. It was demonstrated that the solid-state structure and physical properties of bio-degradable polyesters were widely modified by blending with polyphenols, which can form strong hydrogen bonds through their phenol hydroxyl groups with the carbonyl groups of polyesters.