Biodegradable Polyesters: Synthesis and Physical Properties
This chapter summarizes the synthesis and physical properties of the main members of the biodegradable polyesters family, with special reference to their biodegradability behavior in different environments. Polyesters constitute a large group of biodegradable polymers intended for use in medicine and for the environment protection. Biodegradable polyesters are versatile group of polymers with a range of thermal, mechanical and degradation properties which can easily be tailored to suite a particular application. Biodegradable polyesters can be classified according to their origin as natural or synthetic, the later being further divided into those from renewable and those from petrochemical resources. The synthetic routes to most important polyesters from each of these groups and their physical properties are presented. The representative of polyesters from natural origin are poly(hydroxyalkanoate)s. Poly(lactic acid) is an example of a synthetic polyester obtained from renewable resources, while poly(ε-caprolactone) and poly(butylene succinate) are the most important synthetic biodegradable polyesters obtained from petrochemicals. Although aromatic polyesters are not biodegradable, aliphatic-aromatic copolyesters with improved thermal properties and retained biodegradability have been developed. All of these polyesters, together with different copolyesters have been brought to full commercialization, however there is still room for further cost/performance improvements. The application potential of these materials is discussed and selected examples of commercially available polyesters are given. Future trends in the biodegradable polyester synthesis and material design are briefly discussed.