Robust, Fire-Safe, Monomer-Recovery, Highly Malleable Thermosets from Renewable Bioresources

Conventional thermosets are built by nonrenewable fossil resources and are arduous to be reprocessed, recycled, and reshaped due to their permanent covalent cross-linking, and their flammability makes them unsafe during use. Here, for the first time, we synthesized a novel Schiff base precursor from abundant and renewable lignin derivative vanillin and produced malleable thermosets (Schiff base covalent adaptable networks (CANs)) combining high performance, super-rapid reprocessability, excellent monomer recovery, and arbitrary permanent shape changeability as well as outstanding fire resistance. The Schiff base CANs exhibited high glass transition temperatures of similar to 178 degrees C, tensile strength of similar to 69 MPa, tensile modulus of similar to 1925 MPa, excellent flame retardancy with UL-94 V0 rating and V1 rating, and high LOI of similar to 30%. Meanwhile, three Schiff base CANs showed high malleability with the activation energy of the bond exchange of 49-81 kJ mol(-1) and could be reprocessed in 2-10 min at 180 degrees C. These Schiff base CANs provide a prime example to foster the development of advanced thermosetting materials from renewable bioresources.