Multistage rigid and flexible structure-decorated basalt fibers for epoxy resin composites with synergistically enhanced strength and toughness

In this study, we report the construction of a multistage rigid and flexible structure using boron nitride (BN) and MXene (MX, Ti3C2Tx) nanosheets through the conjugation with (3-aminopropyl) triethoxysilane (APTES). The created structure is further utilized to modify basalt fibers (BFs) to obtain BF/epoxy resin (BF/EP) composites via a simple coating process. The rigid two-dimensional materials (2DMs), BN and MX, significantly enhance the roughness of the BF surface, while the silane (APTES) acts as a flexible bridge for linking BFs, BN, and MX. Consequently, the constructed multistage rigid and flexible structure synergistically enhances the strength and toughness of the composite through effective mechanical interlocking, chemical bonding, and multistage energy dissipation. Meanwhile, this complex structure prevents the stress concentration and promotes uniform stress transfer between BFs and EP. This study provides a promising strategy to construct an effective interface layer and achieve high-performance BF/EP composites by introducing 2DMs and a silane linker.