Naturally produced poly(hydroxyalkanoate)s (PHAs) are commercially implemented biodegradable and biocompatible aliphatic polyesters found many applications in biomedical, pharmaceutical, and packaging industries. However, currently high production costs and low production volumes of biologically produced PHAs largely limit their applications as commodity bioplastics. Natural PHAs are isotactic polymers containing a chiral site in each repeating unit, and their properties span a wide range depending on the length of the side aliphatic chain on the β-carbon. In the context of creating a synthetic equivalent of naturally produced PHAs, both high isotacticity and high molecular weight are typically required for practical use. Accordingly, we recently developed a catalyzed chemical synthesis route to perfectly isotactic, highly crystalline, and high molecular weight poly(3-hydroxybutyrate) (P3HB), the most prominent member of PHAs, from racemic cyclic diolide (rac-DL) derived from bio-sourced succinate. With enantiomeric molecular catalysts, kinetic resolution polymerization of rac-DL automatically stops at 50% conversion and yields enantiopure (R,R)-DL or (S,S)-DL with &gt;99% ee and the corresponding poly[(S)-3HB] or poly[(R)-3HB] with high Tm = 175 °C. Furthermore, we have expanded the monomer scope with different R substituents (DLR) and obtained practically more useful crystalline and flexible copolymers, the topic of which will be discussed in this presentation.

Chemical synthesis of crystalline poly(hydroxyalkanoate)s from cyclic diolides

2019 Fall National Meeting

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