Preparation of colored carbon fiber and its color responsiveness

Carbon fiber (CF) exhibits exceptional mechanical properties, thermal resistance, and electrical conductivity, making it widely utilized in aerospace, military, and sports applications. However, due to the absence of polar groups in the graphite-like structure of CF itself, the surface of CF is chemically inert, and it is difficult to color CF with traditional dyes, which limits the color response of CF in the field of optics and in-depth research in the field of sensing. Polystyrene (PS) microspheres of different sizes were deposited on the surface of carbon fiber monofilaments and fabrics by electrophoretic deposition (EPD), which is a simple and fast process. The wavelength of reflection is regulated by the adjustable photonic crystal band gap so that the structural color response can be changed on the surface of carbon fiber. It is found that PS microspheres can be assembled into ordered stacked photonic crystal structures under the action of the applied electric field. The difference in particle size can show different structural colors: such as blue, green, purple, navy blue, and so on. Among them, carbon cloth with 250 nm microspheres was used to obtain higher color saturation. By changing the filling solvent in the microsphere gap, the internal refractive index can also be changed, thus showing a reversible change in color response.