Enhancing interfacial adhesion and mechanical performance of PBO fibers composites through mussel-inspired molecular regulation of interphase structure

Poor interfacial properties are always one of the bottleneck problems limiting the development of the PBO fiber/epoxy composites. To solve this, we demonstrated a mussel-inspired molecular regulation strategy of interphase structure using the layer-by-layer construction of rigid (PDA) and flexible (PEI) molecules without fiber structure damage. The precise control on the molecular scale can maximally increase the roughness and polar functional group on the fiber surface, thus enhance the chemical bonding and the mechanical interlocking of the interfacial adhesion. In comparison with the untreated fiber, the IFSS and ILSS value of fiber with (PDA/PEI)n have an increment of 86.85% and 80.08%, respectively. Besides, the overall mechanical performance, such as impact strength and dynamic thermal-mechanical behavior, was also improved significantly, owing to the improved physical-mechanical attributes of the interphase. In brief, our study presents a non-destructive interface regulation of PBO fiber composite to enhance its interfacial adhesion and mechanical performance and optimize its structure/function integrated design.