Upcycling of BPA-PC into trimethylene carbonate by solvent assisted organocatalysed depolymerisation

In this study, a solvent assisted organocatalysed method for the depolymerisation of bisphenol A-based polycarbonate (BPA-PC) at low temperature is described. It is shown that the selection of a suitable organic catalyst combined with mild conditions allows for the selective formation of trimethylene carbonate (TMC) in high yields (up to 80%) from the depolymerisation of BPA-PC. The key role of 1-methylimidazole as solvent and imidazole as catalyst is demonstrated and the depolymerisation mechanism is elucidated by ¹H NMR spectroscopy. It is also demonstrated that this methodology could be extended to other nucleophiles, leading to the synthesis of different cyclic carbonyl-containing intermediates. Such selective depolymerisation processes under mild conditions represent a unique and interesting approach for valorising plastic waste into complex molecules that are otherwise difficult to synthesise.