Color carbon fiber and its discoloration response

Carbon fibers have been manufactured industrially for several decades and are widely used in the construction of aircraft, racing cars or sports appliances et al. However, carbon fiber showing no response and adaptation to environmental stimulation has prevented the widespread use of this excellent mechanical reinforcement as functional material. Here, we demonstrate that carbon fibers have not only excellent mechanical properties but also intelligent properties with color responsiveness. We coated graphene oxide (GO) on carbon fiber surface, where the two-dimensional GO orderly stack together and self-assemble as a lamellar stacked structure. Such self-assemble GO film exhibits structural color since the stacked structure is analogous to one-dimensional photonic crystals. Specifically, color carbon fiber with GO one-dimensional photonic crystal coating (colored-CF) is realized for the first time by uniformly surface depositing with vacuum filtration method. We further investigated the colored-CF's intelligent color response and associated coloring mechanism, as well as its microstructure, tensile mechanical properties. The results show that GO coating can repair the surface defects of carbon fiber and improve its specific tensile strength and modulus. Moreover, we found that the colored-CF has interesting characteristics of color response under different solvents, temperature and stress. Our approach gives inspiration for a future design of intelligent responsive carbon fiber composite materials.