Enhancing interfacial performance of epoxy resin composites via in-situ nucleophilic addition polymerization modification of carbon fibers with hyperbranched polyimidazole

Abstract A simple and efficient technique was proposed to yield hyperbranched polyimidazole (HBM) on carbon fiber (CF) surface using isophorone diisocyanate (IPDI) and imidazole (MZ) as monomers. The introduced HBM dendrimers dramatically ameliorated the polar groups, roughness and wettability on the fiber surface. The mechanical performances (interfacial shear, interlaminar shear and impact strength) of CF-HBM/epoxy composite were significantly improved by 78.7%, 41.1% and 43.4% compared with untreated CF composites, respectively. Furthermore, this in-situ polymerization process on CF surface could be conducive to improve the single fiber tensile strength, the interface failure behavior and reinforcing mechanism were also explored. This work furnishes a simple and efficient strategy to construct an interface layer with strong chemical interaction and high physical entanglement through in-situ synthesis, which would provide enormous potential in preparing high-performing structural composites.