What is it about?
In this study, we characterized the tensile ice adhesion of bulk water ice cylinders on metal and polymer reference surfaces, as well as on plasma-coated, flat (hydrophobic) and microstructured (superhydrophobic) polyurethane (PU) films. The functionalized PU films are in development for anti- and de-icing surfaces and have been tested in static icing conditions here, as often experienced on built infrastructure, in contrast to dynamic icing conditions like in aerospace. The different test setups and important parameters regarding ice adhesion are reviewed, and this work is sorted accordingly.
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Why is it important?
These functional surfaces are being researched and developed to improve the energy efficiency and effectivity of common anti- or de-icing methods. The applied microstructuring and plasma-coating processes can be combined to a roll-to-roll process for cost-efficient large-scale functionalization of polymer films. Important conclusions can be drawn for the development of effective de-icing surfaces for static icing conditions regarding the different ice fracture scenarios and the most important parameters, like surface wettability, surface topography, elasticity and microcracks within the ice or at the surface-ice interface from local stress concentrations. Theoretical modeling shows that large microcracks at the interface enable complete ice removal with low forces, and thus should be promoted by the surface elasticity and topography. Elasticity is the most important material parameter. Once adhesive fractures are enabled by sufficient elasticity, the surface chemistry of the material becomes important. The most hydrophobic plasma polymers achieve the lowest ice adhesion. Surface topography is the most important material-independent parameter because surface structures can increase or decrease wettability and ice adhesion. Here, the effect of microstructures is the most pronounced. The nanoscale roughness is less important on flat, plasma-coated surfaces, where surface elasticity and chemistry determine ice adhesion. However, it significantly increases ice adhesion on the microstructured PU surfaces by creating a hierarchical topography. While superhydrophobic surfaces are often assumed to be icephobic in all conditions, our findings demonstrate that this is not the case in static icing conditions.
Perspectives
Although these superhydrophobic PU films with microstructures of minimal base diameter D of 35 µm, pitch P of 50 µm and height H of 43 to 70 µm are ineffective for de-icing in static icing conditions, they may exhibit lower ice adhesion for smaller drops or smaller microstructures, for example if a stable Cassie-Baxter state can be maintained. Other structure geometries are currently investigated, including closed-cell microstructures aimed at increased durability, under similar and different (dynamic) icing conditions. Further research is needed to explore additional structure designs and improve our understanding of the complex mechanisms involved in ice adhesion and removal. Modeling the wetting mechanics, ice crystallization, local stress, microcrack length, and ice fracture strength could help identify the optimal structure design for each application and icing condition.
Dr. Philipp Grimmer
Universitat Stuttgart
Read the Original
This page is a summary of: Tensile ice adhesion of bulk water ice on flat and microstructured hydrophobized polymer surfaces vs. reference materials, Surfaces and Interfaces, March 2025, Elsevier,
DOI: 10.1016/j.surfin.2025.106019.
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