Functional and Network PHAs via Stereoselective Polymerization and Tailored Post-Transformation

Incorporation of functional groups into poly(3-hydroxyalkanoate)s (PHAs) is an important strategy to tailor their properties for specific applications, but both scopes of functional groups and the methods of transforming them into tailored PHA materials are currently limited and merit further exploration. Here, we report a catalyst-controlled stereoselective ring-opening polymerization of functionalized propiolactones for the synthesis of vinyl-, allyl-, and propargyl-functionalized PHAs with high syndiotacticity (P_r up to 0.95) and a broad glass and melting transition window (T_g down to -31°C, T_m up to 126°C). Copolymerization of such lactones with β-butyrolactone further enhances PHA's thermal robustness and mechanical toughness. Three different methods have been developed to further transform the functionalized PHAs into creep- and solvent-resistant crosslinked PHA thermosets, dynamic-supramolecular elastomeric PHA networks, and grafted PHAs with hydrophilic and bioactive molecules. PHA functionalization, also uncovers a rare example of PHA supramolecular stereocomplexes via blending an enantiomeric, vinyl-functionalized PHA pair.