Photoinduced Superhydrophilic TiO2–PHEA/PS Photonic Crystal Composites with Vivid Structural Color, Self-Cleaning Ability, and Robust Structure

Due to its high refractive index, photocatalytic activity, and photoinduced superhydrophilicity, TiO 2 has advantages in photonic crystals (PCs). However, the composite of TiO 2 and PCs needs to be calcined at high temperatures, and the structural stability of the composites is poor. In this study, photoinduced superhydrophilic TiO 2 –poly(hydroxyethyl acrylate)/polystyrene (PHEA/PS) PC composites with strong structural colors and self-cleaning are fabricated by coating triethanolamine-modified anatase TiO 2 nanoparticles-hydroxyethyl acrylate on the surface of PS PCs. The ordered arrays can be retained after the superficial layers of PS PCs are filled with TiO 2 –PHEA, and vivid blue, green, and red composites can be obtained. The water contact angles of the composites can be reduced to 3° in 0.4 s, and superhydrophilicity can be maintained for 180 days in a laboratory environment. The declining superhydrophilicity can be restored under UV irradiation. The composites can degrade the adsorbed methylene blue under UV irradiation. Photocatalytic activity and superhydrophilicity impart self-cleaning ability on the composites. The locking of PS arrays by TiO 2 –PHEA enhances the structural stability of the composites, making them resistant to water soaking and washing. Therefore, the composites show prospects for decoration, fabric coloring, and wearable electronic devices.