Ice-droplet and damaged elastomer interface: a closer look using cryo-FIB-SEM

Silicone elastomers have been identified as promising anti-icing coatings due to their low ice adhesion strength. However, their softness has led to concerns about the durability of their icephobicity. To date, studies on the effects of surface damage have yielded mixed results, with both increases and decreases in ice adhesion observed. To examine the interfacial morphology, we use a new method for imaging the contact between ice droplets on damaged PDMS surfaces using cryo-FIB-SEM. PDMS surfaces are damaged by cutting and abrasion. Milling of the interfaces using the FIB reveals both high- and low-real contact area between ice and PDMS, depending on the shape of the asperity on the abraded surface. We find direct evidence for the level of penetration of ice into the scalpel cut. We show that the interfacial contact between ice and damaged PDMS surfaces can exhibit morphologies analogous to both Cassie-Baxter and Wenzel wetting. These interfacial morphologies, shown for the first time in this study, contribute to the ice adhesion strength trends and are fundamental to improving the understanding and design of future elastomer anti-icing coatings.