Mechanisms of ice formation and propagation on superhydrophobic surfaces: A review.

Icephobic surfaces, used as passive anti-icing materials, are in high demand due to the costs, damage, and loss of equipment and lives related to ice formation on outdoor surfaces. The proper design of icephobic surfaces is intertwined with the need for a profound understanding of ice formation processes and how ice propagates over a surface. Ice formation (ice nucleation) and interdroplet freezing propagation are processes that determine the onset of freezing and complete ice coverage on a surface, respectively. Evaluating the nature of these phenomena, along with their interactions with substrate and environmental factors, can offer a step toward designing surfaces having an improved icephobic performance. This review paper is organized to discuss ice nucleation and rate, preferable locations of nucleation, and favorable pathways of freezing (desublimation and condensation-freezing) on superhydrophobic surfaces. Furthermore, as the propagation of ice over a substrate plays a more deterministic role for the complete freezing coverage of a surface than that of ice formation, this review also elucidates possible mechanisms of ice propagation, theoretical backgrounds, and strategies to control this propagation using surface characteristics.