Robust, Superhydrophobic, and Self‐Healing Films with Hierarchical Nacre Mimetics: A High‐Efficiency and “green” Route Based on Solvent‐Free Polyurethane/Modified Graphene Oxide Composites

Superhydrophobic and self-cleaning materials have attracted tremendous attention because of their broad applications. However, it is still challenging to develop excellent films exhibiting both reparable superhydrophobic and robust mechanical properties by an environmentally friendly method. Inspired by a natural nacre structure, the novel multi-layered inorganic-organic films consisting of n-octadecylamine-modified graphene oxide (NGO) and solvent-free self-healing polyurethane synthesized by Diels-Alder reaction (SFPU-DA) are demonstrated. Through the layer-by-layer assembly technology, super-hydrophobic and self-repairing solvent-free polyurethane composite films (NGO/SFPU-DA films) are prepared. The NGO/SFPU-DA composite films exhibit healing of surface creases and cracks within 120 s at 120 degrees C. Meanwhile, the contact angle and sliding angle of the films can be as high as 151 degrees and 8 degrees, respectively. Noticeably, even after 21 times of rubbing, the superhydrophobicity of the obtained films does not significantly reduce. In addition, the tensile strength and peel strength of NGO/SFPU-DA films can reach 22.6 MPa and 88.6 N/30 mm. Moreover, the steel coated with NGO/SFPU-DA films exhibits lower corrosion current density and better corrosion resistance than the single NGO/SFPU-DA film and uncoated steel. The method may provide an effective way to obtain excellent self-cleaning materials with long service life.