Probing the icephobic intervening air layer on superhydrophobic surfaces: A DSC thermal analysis method

The effectiveness of superhydrophobic anti/deicing surfaces hinges on the intervening air layer between water/ice and substrate. However, the evolution and binding state of this buried interface during the freezing-melting cycle remain notoriously difficult to characterize. Herein, we introduce a simple and intuitive method based on conventional differential scanning calorimetry (DSC) to probe this buried interface and the corresponding thermal resistance. By analyzing the ice melting processes on surfaces with identical topography but opposite wettability (Wenzel vs. Cassie-Baxter states), we demonstrated that the slope of the DSC endotherm peak quantitatively reflects the interfacial thermal resistance from the trapped air. This DSC-derived metric is robust against thermal history and clearly distinguishes hierarchical structures from single-scale analogues, correlating with their ice-delaying performance. Crucially, we demonstrate that the benefit of this air layer in reducing ice adhesion dominates its thermal insulation effect in electrothermal deicing, enabling faster and more energy-efficient ice removal. This work establishes DSC as a universal thermal analysis tool for evaluating icephobic surfaces and provides key insights for their rational design.