Synergistic Inorganic–Organic Interfacial Modification for Colored and High‐Performance Carbon Fiber/Polyamide Composites

Limited color expression and inert surface properties are two critical factors that restrict the application of carbon fiber reinforced thermoplastic composites. In this study, we developed an inorganic TiO 2 film on carbon fiber surfaces via atomic layer deposition (ALD) as a coloration structure. Subsequently, an organic polyamide (PA) layer was successfully incorporated onto the TiO 2 ‐coated carbon fibers through surface modification to enhance interfacial bonding and compatibility between the carbon fiber and PA matrix. The results showed that the PA‐modified TiO 2 film demonstrates dual functionality, simultaneously achieving vivid structural coloration and enhancing interfacial performance with the PA matrix. The film thickness can be precisely tuned to produce primary colors like blue, green, and yellow by controlling the number of ALD cycles. The intrinsic bond strength (IBS) increased by 23.62% from 40.81 MPa of TiO 2 film‐coated carbon fiber (ACF) to 50.14 MPa of PA‐modified TiO 2 film‐coated carbon fiber (ASCF). We propose that this method provides an effective approach for developing carbon fibers with multicolor capability and superior interfacial performance.