Preparation of a self-cleaning TiO2-SiO2/PFDTS coating with superamphiphobicity and photocatalytic performance

Coatings with superamphiphobicity and photocatalytic degradation properties to achieve excellent self-cleaning performance have received extensive attention. Herein, TiO2-SiO2 composite particles with micro-/nanoscale hierarchical structures were fabricated by hydrophobic agglomeration. The TiO2-SiO2 was modified with 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (PFDTS), and then it was sprayed onto the surfaces of substrates to obtain TiO2-SiO2/PFDTS coatings. The coating surface exhibited superamphiphobicity and low adhesion properties. The contact angles (CAs) of water, ethylene glycol, glycerol, and hexadecane on the coating surface were 163.5 degrees, 154.6 degrees, 157.3 degrees, and 150.2 degrees, respectively. The slide angles (SAs) of the above droplets on the coating surface were 0.4 degrees, 2.7 degrees, 1.6 degrees, and 11.1 degrees, respectively. In addition, 80.9 % methyl orange solution (10 ppm) was degraded by the TiO2-SiO2/PFDTS under UV irradiation in 60 min, demonstrating an excellent photocatalytic degradation performance. It also had good adaptability to different substrates, liquids with different properties, and outdoor environments. The results of a mechanistic study showed that SiO2 and TiO2 were connected by the carbon chains of modifiers. PFDTS and TiO2-SiO2 might be combined by chemical bonds or surface carbon chains. The hierarchical structure of TiO2-SiO2 and the low surface energy of PFDTS resulted in the superamphiphobic property of the TiO2-SiO2/PFDTS coating.