A facile strategy to form three-dimensional network structure for mechanically robust superhydrophobic nanocoatings with enhanced transmittance.

The mechanically robust nanocoatings with high transmittance and superhydrophobic self-cleaning are widely desired in daily-life and industry. However, to the state-of-art, it is still a great challenge to develop a simple and cost-effective approach to construct a multifunctional nanocoating due to structural confliction and technical limitation. In this work, we successfully fabricated such a multifunctional nanocoating through dip-coating a mixed suspension composed of acid-catalyzed silica sol (ACSS) as binder and hydrophobic silica nanoparticles (HSNs) as building block onto the glass substrate without any post-treatments. The introduction of ACSS highly crosslinked the HSNs and formed three-dimensional network structure, which enhanced the adhesion between HSNs and substrate, and thus significantly improved mechanical robustness of the nanocoatings. Moreover, it also retained enough porosity and surface roughness, thus achieving high transmittance and superhydrophobicity. The optimized nanocoating deposited on the glass slide had high transmittance of 96.17% and superhydrophobic self-cleaning property. It also showed highly mechanical robustness (3H pencil scratching test), enhanced adhesion (class of 4B for tape adhesion test), weatherable, and acidic (pH 5.0)/alkaline (pH 10.0) and thermal (250 °C) stability. The multifunctional nanocoating with the comprehensive performance has great potentials in practical applications.