Nucleation at the contact line observed on nano-textured surfaces

TL;DR

This study demonstrates that nano-scale surface textures promote ice nucleation at the contact line in supercooled water, highlighting the importance of surface roughness at the nanoscale in phase transition processes.

Contribution

It provides experimental evidence that nano-textured surfaces influence nucleation sites, specifically at the contact line, unlike micro-textured surfaces, advancing understanding of surface-induced nucleation.

Findings

Nano-scale textures shift ice nucleation to the contact line.

Micro-scale textures do not affect nucleation location.

Nucleation correlates with characteristic length scales related to line tension.

Abstract

It has been conjectured that roughness plays a role in surface nucleation, the tendency for freezing to begin preferentially at the liquid-gas interface. Using high speed imaging, we sought evidence for freezing at the contact line on catalyst substrates with imposed characteristic length scales (texture). Length scales consistent with the critical nucleus size and with $\delta \sim \tau / \sigma$, where $\tau$ is a relevant line tension and $\sigma$ is the surface tension, range from nanometers to micron. It is found that nano-scale texture causes a shift in the nucleation of ice in supercooled water to the three-phase contact line, while micro-scale texture does not.