Synergism of non-covalent interaction and ZIF-8@GO to improve tribological and mechanical properties of carbon fiber reinforced recyclable indole-based poly(hexahydrotriazine) composites

Existing research on interfacial interactions of recyclable carbon fiber reinforced poly(hexahydrotriazine) (PHT) composites has mainly focused on the study of reinforcing fibers, ignoring the wide range of applications of matrix in advanced friction materials. Herein, polyhedral ZIF-8 was grown in-situ on the GO surface (named as ZIF-8@GO) to improve the load-bearing capacity of GO nanosheets. The ZIF-8@GO with zinc ions and imidazole ions were embedded as interlaminar reinforcement into matrix to construct a non-covalent cation-π interaction with indole-based PHT (In-PHT) matrix, which significantly enhanced the toughness and tensile strength (reached 215.5 MPa) of composites. With the incorporation of armor-shaped ZIF-8@GO reinforcement, compared with the composite without ZIF-8@GO, the wear track width was significantly decreased by 50%. Moreover, the worn surface lubricated by this composite exhibited efficient self-healing property due to the introduction of the polyethylene wax (PEW), and the healed average friction coefficient showed slight changes. Extensive analyses verify that the ZIF-8@GO structure and cation-π interactions across multiscale interfaces can enhance both mechanical strength and wear resistance of recyclable carbon fiber reinforced In-PHT composites (In-PHT-CFRPs). Highlights ZIF-8@GO was embedded as interlayer reinforcement to improve wear resistance. Cation-π interaction across interface enhances interface carrying capacity. Due to strong cation-π bonding, IPEZGC exhibits outstanding tensile strength. PEW was embedded as healing agent to obtain self-healing property.