A novel cation-π coating of carbon fiber for promoting interfacial properties of fiber-based composites

To construct a high-performance fiber-based composite, it is important to ensure a suitable interface existing between fiber and matrix. However, poor interfacial adhesion restrains the performance of carbon fiber composites due to the confined interaction forces between fiber and matrix. Cation-π interactions play an irreplaceable role in the mussel adhesion, offering an alternative strong interaction between substrate and matrix. Hence, inspired by this, on the premise of no damage to fiber's structure, a novel and versatile coating of carbon fiber was obtained by molecule design. The designed cation polymer acting as a strong interfacial linker was coupled with negatively charged carbon fiber via cation-π interactions quickly, resulting in enhanced physical and chemical bonding, which boosts the interfacial adhesion of carbon fiber composites significantly. Benefiting from this coating, the interlaminar shear strength (ILSS) and flexural strength of modified composite were increased by 38.9 % and 83.5 %, respectively. This work provides a new pathway to develop advanced functional coating for fiber-based composites to deal with complex environments.