Synergistic interactions of citric acid grafted β-cyclodextrin and polyethyleneimine for improving interfacial properties of basalt fiber/epoxy composites

Basalt fiber responds well to the global concept of environmental protection due to its attractive superiorities of green and excellent mechanical performance. However, the ultra-low interfacial adhesion strength of fiber-to-matrix deeply restricts its wide application. Moreover, attempts to utilize natural- or bio-materials on basalt fiber towards growth in interfacial adhesion remains in its infancy, if feasible, it would make green materials shine brilliantly. Herein, we install citric acid modified β-cyclodextrin (β-CD) and polyethyleneimine (PEI) on basalt fiber via dipping approach for the first time, which results in 76.9% increment in fiber-to-epoxy adhesion over control fiber. Unique inner hydrophobic and outer hydrophilic conical cavity architecture of β-CD endows interphase with dense ring hydrogen bond band “core”- covalent/ionic bonding “shell” multiple interactions that balance stress transfer and energy dissipation. Additionally, “rigid” β-CD and “flexible” PEI function as crack deflection and stress distribution for gaining stronger interphase of basalt fiber composites. This paper serves to provide a new exploitation for advancing green and high-performance composites.