A non-destructive strategy to construct ZIF-8 interface layer of carbon fiber/hydroxyapatite-epoxy composites

The interface is the transition region between the fiber and the matrix, whose structure and characteristics determine the overall performance and sustained stability of carbon fiber/hydroxyapatite-epoxy (CHR) composites as bone implant materials. Similarly, carbon fibers, as reinforcement, also play an indispensable role in carrying external loads. Therefore, this work focuses on improving the fibers surface in a gentle and non-destructive way to ensure that the reinforcement of both the fibers and the interface is maximized, resulting in excellent mechanical and biotribological properties. In this work, a novel interface layer was designed by introducing zeolitic imidazolate framework-8 (ZIF-8) into CHR with a facile solvent method. The presence of ZIF-8 induces the formation of flower-cluster hydroxyapatite. The complex layer formed by the combination of the polyhedral shape ZIF-8 and the flower-cluster hydroxyapatite enhances the mechanical interlock and chemical interaction between the carbon fibers and the epoxy matrix. It also promotes the penetration and curing process of the epoxy matrix. The tensile strength of ZIF-8 reinforced CHR (ZIF-8@CHR) are 136.97 MPa, which is 38.43 % higher than that of the pristine CHR. And the wear rate (1.18 × 10⁻¹⁴ m³(N·m)⁻¹) of ZIF-8@CHR is decreased by 81.65 %. ZIF-8@CHR with superior mechanical and biotribological properties provides new insights into the biological application of carbon fiber composites as an implant material for fracture fixation or reconstruction.