Bio-inspired structural coloration of carbon fiber based on thin film interference: Synergistically enhancing thermal durability, tensile strength and interface properties of colored fiber

Carbon fiber (CF) is inert to dyes or pigments, thus its products usually exhibit a drab black and unexciting look. The bio-inspired structural coloration may provide a dye-free method to color CF. Herein, inspired by the interference colors of the insect's wing, a dye-free structural coloration method is proposed to color CF. A layer of poly(cyclotriphosphazene- co -4,4′-oxydianiline) film is assembled on the CF surface by in situ polymerization under a mild reaction condition, creating vivid colors based on thin film interference. Moreover, the structural color shows excellent thermal durability due to the good thermo‑oxygen stability of N P heterocycles and cross-linked networks in coloration film. Furthermore, the tensile strength of colored CF and the interfacial adhesion between colored CF and resin are also synergistically improved by 17.1% and 48.7%, respectively, because of the sturdiness and surface chemical activity of coloration film. In brief, the colored CF may have potential in designing and preparing new structural and functional composites.