Anti-Icing Properties of Vertically Aligned TiO2 Nanopillars.

Abstract

Inspired by the superhydrophobic and anti-icing properties of Berberis thunbergii leaves for the first time, a surface with vertically aligned TiO2 nanopillars (VATiO2NPIs) has been developed, which shows excellent anti-icing properties even at -25 °C. The height and diameter of TiO2NPIs arrays were 200 and 70 nm, respectively, and were fabricated using TiO2 atomic-layer deposition in an aqueous solution on an anodized aluminum oxide substrate and modified with stearic acid. The water contact angle measurements for VATiO2NPI-based aluminum surfaces indicated high contact angle (170.2°), low contact angle hysteresis (5°), excellent delay time (385 s), appropriate robustness (>20 cycles of freeze-melt), and low adhesion strength (<95 kPa). The VATiO2NPI surface analyses were done using energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction spectroscopy (XRD), and Fourier transform infrared spectroscopy (FT-IR) methods, and they showed that the stearic acid stably absorbed on VATiO2NPIs. Our results indicated that the long delay time of the heterogeneous nucleation and freezing process could be obtained by the desired structural match between the VATiO2NPI apices and water molecules in the initiation of the heterogeneous nucleation. In this study, smooth apices of the VATiO2NPIs with highly potent morphology presented significant anti-icing properties because of the strong phonon scattering between nanopillars that can interrupt the heat transfer process. Such results are not achievable by conventional anti-icing methods and give new insight into the mechanism of the anti-icing process.