Facile and eco-friendly functionalization of basalt fiber with polyelectrolyte complex toward excellent interfacial adhesion of epoxy composites

In an attempt to increase the interfacial adhesion of basalt fiber/epoxy composites, a surface modification strategy by constructing ternary polyelectrolyte complex consisted of silane coupling agent-phytic acid-polyethyleneimine via dip-coating is proposed for the first time in the present work. The as-prepared functionalized basalt fiber composite exhibits markedly improved interfacial shear strength, with an average value of 81.9 ± 4.5 MPa, 75% augmentation over that of untreated basalt fiber composite. The reinforcing mechanisms are attributed to the multiple interactions of ionic cross-linked network, covalent and hydrogen bonding at interphase, also including the improved wettability and relatively rough fiber surface. Together with facile preparation approach, nature and low-cost material, the ternary polyelectrolyte complex system developed in this paper offers great potential in practical functionalization of basalt fiber, which could be hopefully extended to other high-performance fibers.