Synthesis and depolymerization studies of biohybrid polycarbonates derived from terpenes

We here report the catalytic ring-opening copolymerization of 2-menthene oxide (MO), a terpene-based monomer derived from l-menthol, and CO2 to provide poly(menthene carbonate), PMC, with a maximum molecular weight (Mn) of 10.2 kg mol−1. The terpene monomer MO can also be combined with both limonene oxide (LO) and CO2 in a formal terpolymerization process providing, depending on the monomer feed ratio, different types of biohybrid polycarbonates (PLMC) with different degrees of functionality. These terpolymerizations could be extended to the use of an acyclic terpene oxide and either MO/CO2 or LO/CO2, and a previously reported xylose-derived bicyclic oxetane. A selection of MO/LO based biohybrid PLMCs were conveniently depolymerized under TBD catalysis to regenerate the original mixture (>95%) of terpene oxides thereby providing a suitable starting point for the circular use of these biohybrid macromolecules.