Recyclable, reprocessable, self-healing elastomer-like epoxy vitrimer with low dielectric permittivity and its closed-loop recyclable carbon fiber reinforced composite

Epoxy resin with reprocessable, strong mechanical property and mutil-functions (such as recyclable and dielectric properties) shows great prospects in many applications, but it is still a huge challenge. Herein, we combine siloxanes and dynamic transesterification reaction to fabricate a novel closed-loop recyclable elastomer-like epoxy vitrimer (ETOD-SA) with high stretchability (135%), low dielectric permittivity (2.75), reversible deformation (30 cycles) as well as rapid self-healing (10 min for a 36 μm scratch). The ETOD-SA is optimized to achieve excellent shape memory and reprocessing properties due to dynamic transesterification reactions catalyzed by internal tertiary amines in the structure of ETOD-SA vitrimer. Furthermore, carbon fiber reinforced ETOD-SA composite (ETOD-SA-CF) also exhibits excellent self-healing, shape memory, degradable properties and has prospective application in recyclable carbon fiber reinforced composite. Due to the rapid chemical degradation of ETOD-SA under mild conditions in the presence of ethanol or butylamine, carbon fibers (CFs) of ETOD-SA-CF can be effectively recycled in a closed loop. The performance of recycled carbon fibers are similar to those of original ones, with almost the same chemical structure and mechanical properties. These results provide an important strategy for the development of mutil-functions epoxy vitrimer materials and their practical applications in the closed-loop recycling of CFs from carbon fiber reinforced composites (CFRPs).