Enhanced and accelerated self-healing performance of carbon fiber/epoxy composites with dual dynamic covalent bonds and graphene via near infrared response

The integration of photo-thermal fillers and dual dynamic covalent bonds remains challenging for the fabrication of high-performance self-healable carbon fiber reinforced epoxy (CF/EP) composites. In this work, graphene (GN) reinforced epoxy matrices with boronic ester and Diels-Alder (DA) bonds (GN/FBA-EP, GN/FBA-DA-EP) and corresponding CF/EP composites were fabricated, and their self-healing performance by near infrared (NIR) heating was compared to that of unreinforced epoxy matrices (FBA-EP, FBA-DA-EP) and composites by conventional heating. The presence of N –C O and a negative shift in C C binding energy verified successful integration of GN and dual dynamic covalent bonds in GN/FBA-DA-EP. Compared to thermal responsive FBA-EP (93.01%, 85.97%) and FBA-DA-EP (94.99%, 91.02%), NIR responsive GN/FBA-EP and GN/FBA-DA-EP achieved higher first and second self-healing efficiencies (95.07%, 88.76% and 96.46%, 94.16%). In contrast to GN/FBA-EP containing single boronic ester bonds, dual-dynamic GN/FBA-DA-EP exhibited rapid recovery of cross-scratches under NIR heating, indicating that high photo-thermal conversion efficiency of GN activated the exchange reaction of boronic ester bonds, thereby facilitating the dissociation and rearrangement of DA bonds. Correlative 2D and 3D morphologies revealed that CF/GN/FBA-DA-EP achieved the minimal scratch depth and fastest recovery time under NIR heating compared to CF/GN/FBA-EP, which confirmed the improved first and second self-healing efficiencies (96.98%, 93.15%) from the synergy between GN and dual dynamic covalent bonds. This work presents a strategy for synergistically enhancing and accelerating the self-healing performance of epoxy matrices and CF/EP composites. Download: Download high-res image (331KB) Download: Download full-size image