Poor interfacial compatibility is a key factor limiting the mechanical properties of basalt fiber reinforced polymer composites (BFRPs). Constructing hybrid interfaces that combine rigid nanoparticles with flexible sizing agents presents a promising strategy to enhance these properties. In this study, we first identified the most suitable coupling agent from a series of candidates, including amino, epoxy, and methacryloxy functional groups. Using the selected coupling agent as a flexible sizing agent and inorganic nano‐SiO2 as the rigid component, two types of interfaces were developed: a homogeneous organic/inorganic hybrid interface and a gradient‐modulus structure, which were fabricated via direct deposition and in‐situ growth methods, respectively. The results demonstrated that BFRPs with gradient modulus interface effectively absorb and dissipate crack energy under loading, resulting in significantly improved mechanical properties. The interlaminar shear strength (ILSS), tensile strength, and flexural strength increased to 56.24, 541, and 793 MPa, respectively, representing improvements of 40.81%, 15.35%, and 32.38%. Fracture morphology analysis further confirmed the reinforcement mechanism of the “rigid‐flexible” hybrid interfaces. This work can provide valuable insights for developing high‐performance basalt fiber‐reinforced composites.Highlights
Suitable silane coupling agent was selected for basalt fiber (BF) reinforced epoxy composites.
Organic/inorganic hybrid and gradient modulus interfaces were established.
Uniformly distributed SiO2 and fully covered silane boosts interfacial bonding.
Interfacial, tensile and flexural properties of modified BFRPs all improved.