Enhancing Surface Icephobic Performance via Spontaneous Fracture Characteristics of Ice Crystals Regulated by Structural Scale Under Shear Flow Conditions

Icephobic surfaces are conventionally designed by minimizing ice adhesion; however, whether this strategy remains valid under aerodynamic shear remains poorly understood. Here, we reveal that an external flow field fundamentally alters ice adhesion dynamics by inducing the spontaneous fracture and detachment of ice crystals through aerodynamic shear forces. The ice‐substrate contact area is primarily determined by the initial droplet size prior to freezing, thereby governing the interfacial adhesion force. Furthermore, Ice detachment is controlled by a competitive interplay between the initial crystal size and its growth orientation, which together determine whether the aerodynamic loading is sufficient to overcome interfacial adhesion. Contrary to the conventional expectation that superhydrophobicity facilitates ice removal, the microstructural anchoring effect inherent to superhydrophobic surfaces impedes spontaneous ice detachment, resulting in substantially higher ice retention compared with conventional hydrophobic surfaces. By contrast, hydrophobic surfaces with nanoscale features exhibit a greater capacity to suppress runback‐ice accumulation under flow than conventional hierarchical superhydrophobic surfaces. These findings establish a mechanistic framework for flow‐induced spontaneous ice detachment and redefine an icephobicity design concept from minimizing adhesion toward controlling fracture dynamics.