Interfacial reinforcement strategy of basalt fiber/polymer composite constructed by interlocking interface composed of ZnO nanowires

Basalt fiber (BF) as a promising reinforcing material, is used widely to prepare polymer composite, but poor interfacial interaction with polymer matrix deteriorates the reinforcement effect. Here, a biomimetic "root-like" BF with laterally-grown zinc oxide (ZnO) nanowires was prepared via dopamine surface modification and two-step hydrothermal method. By virtue of the coordination of catechol groups with Zn2+ ions, the polydopamine coating layer provided the strong affinity with the ZnO seeds layer and facilitated the direction growth of ZnO nanowires, with firm immobilization on the BF surface. Accordingly, the robust interlocking interface was successfully constructed in the root-like BF/polymer composite by penetrating laterally-grown ZnO nanowires into polymer matrix, greatly reinforcing the interfacial adhesion. Compared to conventional surface chemical treatment only suitable for a single specific system, the interfacial interlocking effect mainly depended on the formation of the laterally-grown ZnO nanowires, rather than intrinsic properties of polymer components, so as to be applied to a wide range of polymer composites. This can be exemplified by 265% and 197% increases in interfacial strength of the root-like BF-filled polypropylene (PP) and polydimethylsiloxane (PDMS) composite over that of the corresponding pristine BF ones.