TDI/TiO2 hybrid networks for superhydrophobic coatings with superior UV-durability and cation adsorption functionality.

Durability under UV illumination remains as a big challenge of TiO2-based superhydrophobic coatings, with the photocatalytic effect causing degradation of low surface energy material over time resulting in surfaces losing their hydrophobicity. We report surfaces made from tolylene-2, 4-diisocyanate (TDI)/TiO2 hybrid networks that demonstrate superhydrophobicity and superior UV-durability. Structural and morphological studies reveal that the TDI/TiO2 hybrid networks are composed of TiO2 nanoparticles interconnected with TDI bridges, and then encapsulated by a TDI layer. Through controlling the fraction of TDI in the synthesis process, the thickness of the TDI encapsulation layer around the TDI/TiO2 hybrid networks can be varied. When the weight ratio of TDI:TiO2 is 5:1, the superhydrophobicity of the hybrid network surface remains almost unchanged after a month of continuous UV illumination. This hybrid network surface can also clean methylene blue solution through the synergistic effects of cation adsorption and photocatalysis, holding promising potential for applications toward reducing cation pollutions in both liquid and air environments.