Bio-inspired interfacial engineering of carbon fabric@ZIF-67@cobalt phytate towards enhanced fire safety and mechanical properties of epoxy composites

Abstract Carbon fabric-reinforced epoxy composites (EP/CF) are vital structural materials for engineering fields, but the intrinsic trade-off between fire safety and mechanical properties restricts their high-end applications. Inspired by the hierarchical structure of stylophora pistillata, a bio-inspired, interfacially-engineered carbon fabric@ZIF-67@cobalt phytate hybrid (CF@ZIF-67@CoPhy) was synthesized via in-situ ZIF-67 growth and subsequent phytate coordination. Systematic characterizations via Fourier-transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) confirmed the successful fabrication of micro-nano hierarchical interfacial structure on the tailored hybrid. The as-synthesized CF@ZIF-67@CoPhy was incorporated into EP to fabricate advanced composites. The resultant composites exhibited prominently enhanced fire safety, with the limiting oxygen index (LOI) of 35.6%, UL-94 V-0 rating, and 63.4% reduction in peak heat release rate (PHRR). Such outstanding flame-retardant enhancements stemmed primarily from the synergistic catalytic carbonization of ZIF-67 and CoPhy during combustion. Meanwhile, the modified composites achieved significant mechanical reinforcement. Specifically, the tensile strength, flexural strength and impact strength were increased by 35.0%, 30.9% and 54.6%, respectively. The improved mechanical properties were attributed to the significantly strengthened interfacial adhesion and optimized stress transfer between CF and EP. This feasible bio-inspired interfacial strategy efficiently yielded high-performance EP composites with well-balanced fire safety and mechanical properties, expanding their practical engineering applications.