"Researchers had been trying for years to dial down ice adhesion strength with chemistry, making more and more water-repellent surfaces," said Kevin Golovin, a doctoral student in Materials Science and Engineering. "We've discovered a new knob to turn, using physics to change the mechanics of how ice breaks free from a surface."
The University research team, led by Anish Tuteja, Associate Professor of Materials Science and Engineering, initially experimented with water-repelling surfaces, but found that they weren't effective at shedding ice. However, they did noticed something quite unexpected: rubbery coatings worked best for repelling ice, even when they weren't water-repellent. Eventually, they discovered that the ability to shed water wasn't important at all. The rubbery coatings repelled ice because of a different phenomenon, called "interfacial cavitation."
Thin, clear and slightly rubbery to the touch, the spray-on coating formulation allows ice to slide off equipment, airplanes and car windshields with only the force of gravity or a gentle breeze. The coating is inexpensive and durable.
The research team also found that by slightly altering the smoothness and ‘rubberiness’ of the coating, they could fine-tune its degree of ice repellency and durability. Softer surfaces tend to be more ice-repellent but less durable, while the opposite is true for harder coatings. Golovin believes that flexibility will enable them to create coatings for a huge variety of applications.
"An airplane coating, for example, would need to be extremely durable, but it could be less ice-repellent because of high winds and vibration that would help push ice off," Golovin said. "A freezer coating, on the other hand, could be less durable, but would need to shed ice with just the force of gravity and slight vibrations. The great thing about our approach is that it's easy to fine-tune it for any given application."
The new coating could also lead to big energy savings in freezers, which today rely on complex and energy-hungry defrosting systems to stay frost-free. An ice-repelling coating could do the same job with zero energy consumption, making household and industrial freezers up to 20 percent more efficient.
"I think the first commercial application will be in linings for commercial frozen food packaging, where sticking is often a problem. We'll probably see that within the next year," Tuteja said. "Using this technology in places like cars and airplanes will be very complex because of the stringent durability and safety requirements, but we're working on it." The coating is detailed in a new paper published in the journal Science Advances.
I love to see new approaches like this. I know the real breakthroughs are not frequent and take years of hard work and diligence. And then - every once in a while - a novel approach or breakthrough does occur. I do hope this work develops into commercial viability. It sure looks good!