Micro cross-linking strategy with dynamic covalent bond for high-performance epoxy-based thermoplastic polymer and polymer composites

Developing high-performance thermoplastic polymer and polymer composites with convenient manufacturing and recycling performance still presents a challenge. Herein, a micro cross-linking strategy was introduced to balance the relationship between processability and mechanical properties of thermoplastic polymer. Though this strategy, a polyfunctional aromatic amine containing disulfide bond (AFD) was used as chain extender to prepare the micro cross-linking thermoplastic epoxy (MTPE). By controlling the AFD content, MTPE with various cross-linking densities were successfully synthesized. Compared with linear thermoplastic epoxy (TPE), the glass transition temperature and tensile strength of MTPE, and the tensile properties of carbon fiber reinforced MTPE composites (CF/MTPE) was significantly increased by 11.5 %, 16.3 % and 7.8 %, respectively. And, due to the dynamic exchange characteristics of disulfide bonds, the processing temperature of MTPE could be consistent with that of TPE. Additionally, full-length carbon fibers could be conveniently and rapidly recovered from CF/MTPE composites. Due to the excellent compatibility between MTPE and difunctional epoxides, the fine powder of CF/MTPE composites could be treated as a filler to enhance the mechanical properties of difunctional epoxides-based thermosets. This micro cross-linking strategy provides a new way for producing high-performance thermoplastic polymers and offers valuable insights into the recycling of composite materials.