ABSTRACT
Polyhydroxyalkanoates (PHA) are natural polyesters collected as intracellular granules as a result of a metabolic stress upon unbalanced growth, owing to a limited supply of a necessary nutrient and to the presence of an excess of a carbon source. PHAs have material properties ranging from rigid and highly crystalline to elastic, rather amorphous, and flexible. PHAs can be functionalized by biological and chemical modification reactions. The chapter presents up-to-date PHA synthesis, functionalization, and diversification. Polyhydroxybutyrates, the most common PHA, has a major problem, which is its rapid thermal degradation near its melting temperature. Telechelic PHAs are mostly synthetized from natural PHAs using high-molar-mass precursors. The chemical modification of telechelic PHAs can be achieved by several methods such as transesterification, carboxylation, hydroxylation, epoxidation, quaternization, sulfonation, chlorination, or attachment of vinyl groups. Biodegradable polymers gained very high attention by the governments of the world because of environmental and petroleum reserve limitation issues.
