Degradation of Natural and Artificial Poly[(R)-3-hydroxyalkanoate]s: From Biodegradation to Hydrolysis

Abstract

Biodegradability of polymers has drawn much attention as a solution to problems concerning the global environment and biomedical technologies. Poly[(R)-3-hydroxybutyrate] and its copolymers are representative biodegradable polyesters which can be degraded in natural environments such as soil, sludge, freshwater, and seawater file://Users/cecily/Documents/Research/Literature/Cecily-Research.enlp/Cecily-Research.Data/PDF many microorganisms utilize the degraded products as a carbon source. The ability to degrade poly[(R)-3-hydroxyalkanoate]s (PHAs) is widely distributed among fungi and bacteria and depends on the extracellular PHA depolymerases, which are carboxyesterases, and on the physical state of the polymer (amorphous or crystalline). Intracellular depolymerase systems lead to CO2 and H2O when bacteria need energy or carbon sources. All polyesters are susceptible degradation by simple hydrolysis to some extent. The degradation rate is very dependent on the chemical structure and the crystallinity of the materials. One way to obtain more hydrophilic PHAs consists in the introduction of specific functions into the macromolecular side chains. The combination of bioconversion and organic chemistry allows modulation of the physical properties of these bacterial polyesters, such as solubility, hydrophilic–hydrophobic balance, and water stability, from the perspective of biomedical applications.