Superhydrophobic and photocatalytic PDMS/TiO2 coatings with environmental stability and multifunctionality

Maintaining the long-term stability of TiO2-based superhydrophobic (SH) coatings remains a considerable challenge because of the strong photocatalytic properties of TiO2. The organic SH components that surround the TiO2 particles are often degraded when the coating is exposed to UV light, thus destroying the anti-wettability properties. In our work, we fabricated a UV-stable SH coating from dispersions of polydimethylsiloxane (PDMS) and TiO2 nanoparticles, which can be easily applied to a wide range of substrates by spray coating. The resulting films possess SH properties due to the combination of the low surface energy of PDMS, and the hierarchical structure resulting from the different aggregation sizes of TiO2 nanoparticles. The coating can recover its SH properties after exposure to organic pollutants, which can be photo-degraded and removed by TiO2. The coating is highly durable due to the crosslinked PDMS, and SH properties are retained after 7 days under UV light, or 3 months exposure to sunlight in outdoor conditions. We also demonstrate the coating’s good resistance to corrosion, water impact, and high temperature, all while maintaining superhydrophobicity. This multifunctional SH coating represents a very promising material for commercial and industrial coatings applications.