A team of researchers led by Indian-American scientist has developed an ice-repellent spray-on formula that is durable, inexpensive with a rubber touch added to it. It could make ice slide off equipment, airplanes or car windshields with only the force of gravity or a gentle breeze.
"We've discovered a new knob to turn, using physics to change the mechanics of how ice breaks free from a surface," said one of the researchers Kevin Golovin, a doctoral student at the University of Michigan in US.
Made of a blend of common synthetic rubbers, the formula marks a departure from earlier approaches that relied on making surfaces either very water-repellent or very slippery.
The team had initially looked to expand on the capabilities of water-repellent materials, but experiments kept showing these materials cannot be sufficiently re-engineered to shed ice as well as they do water.
Thus, during their experiments, the researchers noticed that the rubbery coatings worked best for repelling ice, even when they weren't water-repellent. Eventually, they discovered that the rubbery coatings repelled ice because of a phenomenon called "interfacial cavitation."
"Nobody had explored the idea that rubberiness can reduce ice adhesion," said lead researcher Anish Tuteja, associate professor at the University of Michigan.
The new approach makes it possible to dramatically improve durability, and the formula stood up to a variety of lab tests including peel tests, salt spray corrosion, high temperatures, mechanical abrasion and hundreds of freeze-thaw cycles.
The team also found that by slightly altering the smoothness and rubberiness of the coating, the degree of ice repellency and durability can be fine tuned.
Softer surfaces tend to be more ice-repellent but less durable, while the opposite is true for harder coatings.
"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," he added.
The findings of the study are detailed in the journal Science Advances.
The thin, clear and slightly rubbery touch of this coating could have major implications in industries like energy, shipping and transportation, where ice is a constant problem in cold climates, the researchers concluded.