Ice wreaks havoc on surfaces, but we might have a new way to prevent it building up. Scientists at Northwestern University have shown that textured surfaces with thin layers of graphene oxide can stay completely frost-free for long periods.
When frost, ice and snow build up on surfaces, it can cause all kinds of trouble. Roads and sidewalks become slippery and dangerous, power lines can be damaged, and the aerodynamics of aircraft wings can be affected. Countering ice buildup usually involves salt, heat or good old fashioned shovels, but those come with environmental, energy and effort costs, respectively.
Now, scientists at Northwestern University have developed a new way to make frost-repelling surfaces. It starts with a texture inspired by leaves, which have tiny peaks and valleys that prevent frost from spreading uniformly across the surface. In a 2020 study, the team found that adding this kind of surface structure, on the scale of millimeters, helped reduce frost formation by up to 80%.
In the new study, the researchers took it a few steps further. They added a very thin layer of graphene oxide, just 600 micrometers thick, to the surface of the valleys, which were just 5 mm (0.2 in) wide between each peak.
“Graphene oxide attracts water vapor and then confines water molecules within its structure,” said Kyoo-Chul Kenneth Park, lead author of the study. “So, the graphene oxide layer acts like a container to prevent water vapor from freezing. When we combined graphene oxide with the macrotexture surface, it resisted frost for long times at high supersaturation. The hybrid surface becomes a stable, long-lasting, frost-free zone.”
Sure enough, the new surface resisted 100% of frost formation for over 150 hours, which is almost a week. That’s far longer than most other types of ice-resistant coatings, and it does so passively, requiring no electricity or active components. The surface itself should be long-lasting too.
“Most other anti-frosting surfaces are susceptible to damage from scratches or contamination, which degrades surface performance over time,” said Park. “But our anti-frosting mechanism demonstrates robustness to scratches, cracks and contaminants, extending the life of the surface.”
The team says that the new surface structure could be applied anywhere frost becomes a nuisance – on vehicle and aircraft surfaces, power lines, the insides of freezers, maybe even sidewalks and roads.
The research was published in the journal Science Advances.
Source: Northwestern University