Angle-Independent Structurally Colored PS@TiO₂ Film with Excellent Underwater Superoleophobicity in Harsh Environments

Chemical pigments are damaging to the environment; however, a nontoxic substance (including TiO2 and SiO2) often appears white because of the incoherent multiple scattering. The addition of small black substances can enhance the structural color of the amorphous system. Herein, colored amorphous photonic crystals (APCs) with angle-independence were fabricated by TiO2-coated polystyrene core–shell nanoparticles (PS@TiO2 NPs) via a healthy and time-saving sprayed method. Compared with generally used collide materials, such as PS and SiO2 NPs with smooth surfaces, the rough TiO2 NPs shell structure has significant advances for the underwater oil-repellent property. Thanks to the TiO2 NPs adhered to PS spheres, the multiscale roughness was enhanced and the PS@TiO2/CB film was endowed with excellent underwater superoleophobicity without other extremely hydrophilic chemical compositions. Furthermore, the waterborne polyurethane improves the robustness of the film. This film is free from the adhesion of oil in the water, which can be employed into diverse undersurface systems and may boost the promising applications of APCs.