Reversible Amidation Chemistry Enables Closed‐Loop Chemical Recycling of Carbon Fiber Reinforced Polymer Composites to Monomers and Fibers

Abstract

Highly efficient recycling of carbon fiber reinforced polymer composites into monomers and fibers is a formidable challenge. Herein, we present a closed‐loop recycling approach for carbon fiber reinforced polymer composites using reversible amidation chemistry, enabling the complete recovery of intact carbon fibers and pure monomers. The polymer network, synthesized by amidation between a macromonomer linear polyethyleneimine and a bifunctional maleic anhydride cross‐linker, serves as matrices for the construction of composites with exceptional mechanical properties, thermal stability and solvent resistance. The matrices can be fully depolymerized under the acidic condition at ambient temperature, allowing for the effective separation and recovery of both carbon fibers and the two monomers. The reclaimed carbon fibers retain nearly identical mechanical properties to pristine ones, while pure monomers are recycled with high separation yields (> 93%). They can be reused in the manufacture of new composites for multiple cycles, whose mechanical properties recover over 95% of their original properties. This line of research presents a promising approach for the design of high‐performance and sustainable thermoset composites, offering significant environmental and economic benefits.