Carbon fiber (CF) reinforced matrix composites have wide application prospect, however, the interfacial adhesion of composites is weak due to smooth and chemically inert of CF surface. To settle this problem, two kinds of synergistic hierarchical reinforcements with multiscale “rigid-flexible” structures [CF-graphene oxide (GO)-carbon nanotubes (CNTs)- polyamide (PA) and CF-CNTs-GO-PA] were fabricated through simple esterification and anionic polymerization reactions. The effects of the interface thickness and grafting sequence on the interfacial properties of the composites were explored. The interfacial shear strength (IFSS) of the CF-GO-CNTs-PA/resin composites was 88.3 MPa, which exceeded those of CF, CF-GO-CNTs, CF-GO-PA, and CF-CNTs-GO-PA by 80.9%, 11.5%, 2.3%, and 1.4%, respectively. This was mainly ascribed to the thicker gradient interface layer, the synergistic effects of GO and CNTs, the rigid and flexible structure, as well as the interfacial interactions and mechanical interlocking effect in the CF-GO-CNTs-PA/resin composite. This work provides a novel concept for the construction of interfaces suitable for advanced CF composites with different structures.

碳纤维（CF）增强基复合材料具有广泛的应用前景，但由于CF表面光滑且化学惰性，复合材料的界面粘合力较弱。为了解决这个问题，两种具有多尺度“刚柔”结构的协同分层增强材料[CF-氧化石墨烯（GO）-碳纳米管（CNTs）-聚酰胺（PA）和CF-CNTs-GO-PA]通过简单的酯化和阴离子聚合反应。探讨了界面厚度和接枝顺序对复合材料界面性能的影响。CF-GO-CNTs-PA/树脂复合材料的界面剪切强度（IFSS）为 88.3 MPa，超过了 CF、CF-GO-CNTs、CF-GO-PA 和 CF-CNTs-GO-PA 的界面剪切强度（IFSS）分别为 80.9%、11.5%、2.3% 和 1.4%。这主要归因于较厚的梯度界面层、GO和CNTs的协同效应、刚性和柔性结构，以及CF-GO-CNTs-PA/树脂复合材料中的界面相互作用和机械互锁效应。这项工作为构建适用于具有不同结构的高级 CF 复合材料的界面提供了一个新概念。