Bioinspired Laser-Textured Aluminum Surfaces for Anti-Icing: Coupled Effects of Hydrophobic Coating Chemistry and Surface Morphology

Natural water-repellent surfaces use hierarchical texture and low surface energy to minimize liquid adhesion, and this principle has inspired engineered superhydrophobic surfaces for passive anti-icing. However, whether such bioinspired water-repellent architectures remain beneficial during freezing and ice detachment depends on the stability of the wetting state and on the interaction between surface texture and coating chemistry. This study evaluates the anti-icing performance of smooth and laser-textured 1050A aluminum surfaces functionalized with different hydrophobic agents. Freezing delay measurements at −18 °C and ice adhesion strength measurements at −20 °C were conducted, together with wettability, surface free energy, roughness, and morphology analyses, to compare different coatings on identical morphologies and to isolate the effect of laser-generated texture for the same coating chemistry. On smooth surfaces, fluorinated alkyl phosphonic acid coating provided the largest reduction in ice adhesion strength, decreasing it by approximately 72% relative to the non-functionalized reference, while alkyl phosphonic acid coating reduced it by approximately 50%. In contrast, polydimethylsiloxane showed the longest freezing delay, with a mean value of 907 s, whereas the fatty acid-based coatings exhibited shorter freezing delays than the bare reference surface. On laser-textured surfaces, all coatings initially produced highly water-repellent wetting states. However, the differences in ice adhesion strength were markedly reduced and no longer followed the same ranking as on smooth surfaces. Polydimethylsiloxane again exhibited the most favorable freezing delay, while fluorinated alkyl phosphonic acid showed the poorest performance on the textured substrate. These results show that the bioinspired superhydrophobic state created by laser texturing does not by itself guarantee improved anti-icing performance, as under icing conditions, texture-mediated wetting, local liquid penetration, condensation or frost formation inside the texture, and mechanical interlocking can dominate over the nominal low-surface-energy chemistry.