A mussel-inspired interfacial engineering strategy for enhancing the mechanical properties of aramid fiber/epoxy composites

The interfacial strengthening of aramid fiber/epoxy (AF/EP) composites is primarily challenged by the significant modulus mismatch between the fibers and matrix. Furthermore, the inherent chemical inertness of AFs results in a scarcity of surface-active sites, which leads to weak interfacial interactions and inefficient stress transfer. Consequently, the overall mechanical performance of fibrous composites was severely limited. Inspired by “mussel adhesive protein”, this study designed and synthesized an amphiphilic organic molecule, dipentaerythritol-2-amino-4-hydroxy-6-methylpyrimidine-hexylisocyanate (DiPE-UPy) as the mussel protein-inspired adhesive, and employed graphene oxide (GO) nanosheets which provide high stiffness and a large specific surface area as ordered crystalline structures in proteins to construct an organic-inorganic hybrid sizing agent via a co-assembly strategy. The hybrid coating established a high-density cross-linking network between AFs and epoxy resin through multiple interactions, including quadruple hydrogen bonding and π-π stacking, thus significantly enhanced interfacial compatibility and synergistic stress transfer efficiency. The results demonstrated that the interfacial shear strength, flexural strength, and tensile strength of the modified AF/EP composites were increased by 87.47 %, 63.02 %, and 44.75 %, respectively, compared to the blank UAF/EP composite. The bio-inspired interface construction strategy provides an efficient and scalable new approach for developing high-performance AF-reinforced composites.