Biomimetically-engineered FRP composites: integration of nanostructured resin matrix with hybrid fiber networks towards ultrahigh chemical stability and mechanical strengthening

The widespread application of fiber-reinforced polymer (FRP) composites in aggressive marine concrete environments was hindered by the bottleneck of low interlayer shear strength and poor alkali corrosion resistance. In this work, a dual biomimetic strategy, inspired by the superhydrophobic architecture of lotus leaves and the gradient vascular bundles of bamboo, is proposed to engineer hybrid FRP composites with synergistic nanointerfaces and macro-scale fiber networks. This design integrates tetraethyl orthosilicate-polymethylhydrosiloxane (TEOS-PMHS)-modified graphite/carbon nanotubes as hydrophobic nanofillers into the epoxy matrix, alongside a bamboo-mimetic gradient arrangement of carbon/glass fibers. The resulting biomimetically-engineered FRP (BE-FRP) bars achieve an unprecedented interlaminar shear strength of 75.4 MPa and retain 80.5% of their strength after 120 days in seawater sea-sand concrete (SWSC) solution at 60°C - representing a 280% increase in shear strength and 160% higher retention ratio than conventional GFRP bars. Such enhancements stem from multi-scale interfacial synergies: nano-scale hydrophobic barriers inhibit corrosive ion ingress and reinforcing the cohesive strength between the epoxy resins and fibers, while the gradient fiber network suppresses crack propagation through mechanical interlocking and stress redistribution. This biomimetic hybridization strategy provides a universal paradigm for designing next-generation composites that simultaneously transcend multiple property trade-offs in extreme environment.