Review on the Synthesis, Recyclability, Degradability, Self-Healability and Potential Applications of Reversible Imine Bond Containing Biobased Epoxy Thermosets

Epoxy thermosets need to be designed for simple recycling and biomass resource utilization in order to be fully sustainable building materials. The development of covalent adaptive networks (CANs) using adaptive covalent chemistry (ACC) may be helpful in this regard. Several reversible covalent bonds are incorporated into the epoxy polymer to overcome the challenge of reprocessability or recyclability, degradability and self-healability. The imine bond, also referred to as the Schiff base, is one of the reversible covalent bonds that can participate in both associative and dissociative reactions. This opens up possibilities for mechanical and chemical recycling as well as self-healing. This review summarises the progress related to the synthesis and mechanical and thermal properties of epoxy thermosets based on reversible imine bonds derived from different sustainable resources over the past few decades. The feedstocks, physical and thermal properties, recycling conditions, degradability and self-healability of the biomass epoxy thermosets are addressed along with the main obstacles, prospective improvements and potential applications.