Carbon nanotube (CNT) films are well known for their ultra-low density, high porosity, tunable conductivity and a number of other desirable characteristics. Integrating CNT films into composite materials would endow these structural materials with multifunctionality while adding only negligibly to their weight. This review introduces the fabrication of CNT films and presents the state-of-the-art research advances of CNT-film-enabled functions of composite materials, such as resistive heating, lightning strike protection, electromagnetic interference shielding, and structural health monitoring. Future research on CNT-film-based multifunctional composite materials is also discussed.

Multi-scale “rigid-soft” material coating has been an effective strategy for enhancing the interfacial shear strength (IFSS) of carbon fibers (CFs), which is one of the key themes in composite research. In this study, a soft material, chitosan (CS), and a rigid material, carbon nanotubes (CNTs), were sequentially grafted onto the CFs surface by a two-step amination reaction. The construction of the “rigid-soft” structure significantly increased the roughness and activity of the CFs surface, which improved the mechanical interlocking and chemical bonding between the CFs and resin. The interfacial shear strength (IFSS) of the CS- and CNT-modified CFs composites increased by 186.9% to 123.65 MPa compared to the desized fibers. In addition, the tensile strength of the modified CFs was also enhanced by 26.79% after coating with CS and CNTs. This strategy of establishing a “rigid-soft” gradient modulus interfacial layer with simple and non-destructive operation provides a valuable reference for obtaining high-performance CFs composites.