Catalytic disconnection of C–O bonds in epoxy resins and composites

Abstract Fibre-reinforced epoxy composites are well established in regard to load-bearing applications in the aerospace, automotive and wind power industries, owing to their light weight and high durability. These composites are based on thermoset resins embedding glass or carbon fibres 1 . In lieu of viable recycling strategies, end-of-use composite-based structures such as wind turbine blades are commonly landfilled 1–4 . Because of the negative environmental impact of plastic waste 5,6 , the need for circular economies of plastics has become more pressing 7,8 . However, recycling thermoset plastics is no trivial matter 1–4 . Here we report a transition-metal-catalysed protocol for recovery of the polymer building block bisphenol A and intact fibres from epoxy composites. A Ru-catalysed, dehydrogenation/bond, cleavage/reduction cascade disconnects the C(alkyl)–O bonds of the most common linkages of the polymer. We showcase the application of this methodology to relevant unmodified amine-cured epoxy resins as well as commercial composites, including the shell of a wind turbine blade. Our results demonstrate that chemical recycling approaches for thermoset epoxy resins and composites are achievable.