Enhanced Interfacial Adhesion and Dynamic Seawater Durability of Basalt Fiber/Epoxy Composites via PDA-Assisted In Situ Growth of UiO-66-NH2

Durable basalt fiber-reinforced polymer (BFRP) composites are needed for marine and offshore structures, where seawater exposure and hydrodynamic shear progressively degrade the fiber–matrix interface. To address this challenge, a hierarchical polydopamine (PDA)/UiO-66-NH2 interphase was constructed on basalt fibers through PDA-assisted in situ growth. PDA served as an adhesive interlayer and nucleation platform, enabling dense anchoring of UiO-66-NH2 crystals. Compared with that of unmodified fibers, the optimized interface increased single-fiber tensile strength by 23.9% and interfacial shear strength by 67.9%. At the laminate level, flexural strength and interlaminar shear strength increased by 43.5% and 44.6%, respectively, accompanied by a transition from interfacial debonding to predominantly resin cohesive failure. Under dynamic simulated-seawater exposure, the modified composites showed lower mass change and improved mechanical property retention. The enhanced performance is attributed to improved interfacial interactions, micro-/nanoscale mechanical interlocking, and delayed ingress of corrosive species. This work provides an interface engineering strategy for mechanically robust and seawater-durable BFRP composites.