Regulating the stereomicrostructure, circularity and functionality of synthetic PHAs

Biodegradable plastics, especially those that can biodegrade in uncontrolled enviroments, are of importance to help curb the global plastics crisis. Poly(3-hydroxyalkanoate)s (PHAs), which can be either microbially or chemically synthesized, are one of the rare classes of plastics that can biodegrade under both managed and unmanaged conditions. Besides this exceptional upside, PHAs can also be tuned to exhibit thermal, mechanical, and optical properties of commodity polymers including polyolefins, and they can be designed to be chemically recyclable towards a circular PHA economy or functionalized to acquire additional, diverse and/or improved properties. To enable such modularity in chemocatalytic PHAs, the development of stereoselective and controlled molecular catalysts, as well as the design of monomer structures and polymerization processes, is of primary importance. In this context, this Perspective article focuses on three recent advancements, including PHA stereomicrostructural engineering, melt-processability and chemical recyclability, and chemical functionalization.