Robust, Transparent, and Superhydrophobic Coating Fabricated with Waterborne Polyurethane and Inorganic Nanoparticle Composites

We report the fabrication of a robust, transparent, and superhydrophobic organic–inorganic composite coating with simple, low-cost, effective, and environmentally friendly characteristics. First, a waterborne polyurethane (WPU) emulsion and silica fluoride (F-SiO2) nanoparticle dispersion were synthesized. Subsequently, the organic–inorganic superhydrophobic surfaces with low surface energy were constructed by spraying, in order, the WPU emulsion and F-SiO2 nanoparticle dispersion on substrates. The robust composite coating had superhydrophobicity and good optical transparency, in which the WPU provided a strongly adhesive elastic substance for the anchoring of superhydrophobic F-SiO2 nanoparticles to further construct a mechanically and chemically resilient nanocomposite coating. After 250 cycles of abrasion, a long period of ultraviolet irradiation, and oil-pollution and cross-cut tests, the nanocomposite coating still exhibited excellent properties including good self-cleaning, transparency, abrasion resistance, aging resistance, and strong adhesion. Even after being oil-contaminated, the WPU/F-SiO2 composite coatings still possessed superhydrophobic properties, showing their future application as self-cleaning surfaces and protective coatings for various substrates.