Controlled Synthesis of TiO₂ Nanotube Array-Based Slippery Liquid-Infused Porous Surfaces with Durable Liquid-Holding...

The relationship between the nanostructures and the long-term properties of slippery liquid-infused porous surfaces (SLIPS), including liquid-holding ability and anti-icing performance, is an important issue, but poorly systematically elucidated. Herein, we used TiO₂ nanotube arrays with exquisitely designed diameter and length as a model system to investigate the effects of the structural parameters on the long-term properties of SLIPS. The TiO₂ nanotube arrays with diameters ranging from 40 to 110 nm and lengths from 3 to 12 μm were fabricated for the first time on Ti substrates via an optimized anodic oxidation method and then infused with a lubricant to form SLIPS with superior slippery properties. The contact angle hysteresis (CAH) of TiO₂ SLIPS after 20 min high-speed centrifugation or 7 day water shearing was lower than 4° or as low as 8°, respectively, indicating the excellent liquid-retention property of TiO₂ SLIPS. We propose that the long-term liquid-holding ability of the obtained TiO₂ SLIPS is attributed to the synergistic effect of the small nanotube diameter (strengthening capillary force) and the large porous volume (enhancing lubricant storage). Furthermore, we find that icing on TiO₂ SLIPS can be delayed for more than 24 h at low temperature (-22 °C), indicating the superior anti-icing ability derived from the lubricant film maintained by the optimized structures. The results reveal that structural parameters, including the nanotube diameter and length and porous volume that can be used to hold lubricant, significantly influence the slippery property, liquid-holding property, and long-term anti-icing property of SLIPS.