Ice adhesion on hydrophilic and hydrophobic surfaces: Visualization with Cryo-FIB-SEM

• Cryo-FIB-SEM used to image ice-substrate interface at nanoscale resolution. • Ice adhesion compared on hydrophilic, hydrophobic, and hybrid surfaces. • Clear interfacial gaps observed on PDMS and patterned hybrid surfaces. • FIB-induced ice transformation and sublimation effects documented. Ice adhesion on solid surfaces poses significant challenges in aviation, infrastructure, and marine applications, particularly in cold climates. Understanding the interfacial bonding mechanisms between ice and different substrate types is crucial for designing effective icephobic surfaces. This study investigates the adhesion behavior of ice on hydrophilic, hydrophobic, and hybrid surfaces using advanced visualization techniques. A novel application of Cryogenic Focused Ion Beam Scanning Electron Microscopy (Cryo-FIB-SEM), performed on a Thermo Fisher Scientific Helios 600i instrument, enabled direct observation of the ice-substrate interface at nanoscale resolution under cryogenic conditions. Four sample types were prepared: (1) rime ice on a roughened hydrophilic aluminum surface, (2) glaze ice on the same aluminum surface, (3) glaze ice on a hydrophobic polydimethylsiloxane (PDMS)-coated surface, and (4) glaze ice on a hybrid Al/PDMS-patterned substrate. Cryo-FIB-SEM revealed distinct interfacial behaviors: ice formed strong, continuous bonding on hydrophilic surfaces, with no visible interfacial gaps, consistent with reported adhesion strengths for aluminum surfaces typically ranging from approximately 0.2 to 0.9 MPa depending on ice type and temperature. While hydrophobic surfaces showed clear separation gaps and reduced contact, indicating significantly lower effective adhesion associated with reduced mechanical interlocking and weaker interfacial bonding. The hybrid surface demonstrated localized ice detachment on PDMS regions and adhesion on aluminum, suggesting tunable adhesion properties based on surface patterning and chemistry. The use of Cryo-FIB-SEM enabled the identification of crystalline structures (Ice Ih) and morphological transitions caused by focused ion beam interaction, offering unique insights into ice behavior at micro- and nanoscale levels. By directly visualizing interfacial continuity and gap formation, this study provides quantitative-context-supported nanoscale evidence of adhesion mechanisms. This work highlights the power of cryo-microscopy in advancing our understanding of ice adhesion phenomena and supports the development of tailored surfaces for anti-icing applications.