Anyone who's tried to travel by air during winter might know how frustrating it can be to sit on the tarmac while ice is removed from the wings of the aircraft. A truck spraying the wings with a de-icing agent might get the job done, but it also means precious travel time is wasted. To reduce downtime, scientists have developed a material that secretes a slick substance when temperatures drop to prevent ice from sticking to the wings in the first place.
Labeled self-lubricating organogels, or SLUGs, the substances the team developed include a gel and liquid-repelling substance held in a matrix of silcone resin. To attach it to the wings, the SLUG is cured and applied as a semi-transparent solid film covering. When the temperature drops below freezing, the material secretes a liquid-repellent substance that is so slippery ice can't stick to it. Once the temperature jumps back above freezing, the liquid-repellent secretion is absorbed back into the film.
According to researcher Chihiro Urata, Ph.D., from the National Institute of Advanced Industrial Science & Technology in Japan, the idea for the coating came about after observing slugs in the environment.
"Slugs live underground in soils when it is daytime and crawl out at night," Urata says. "But we never see slugs covered in dirt. They secrete a liquid mucus on their skin, which repels dirt and the dirt slides off. From this we started focusing on the phenomenon called syneresis, the expulsion of gel from a liquid."
While the self-lubricating organogels show potential, they're not the only anti-icing technologies under development. Researchers at the University of Michigan have developed a rubber-based coating that uses the principle of "interfacial cavitation" to prevent ice adhering to car windshields and numberplates, while Harvard researchers have attempted to tackle the problem by mimicking the water-repellent legs of mosquitos and water striders with silicon nanoscale shapes and patterns.
Scientists have even looked to desert beetles and their clever water gathering techniques in an attempt to find a suitable coating for aircraft wings, wind turbines and car windscreens.
According to Urata, SLUGs have plenty of potential beyond airplane wings, with other potential applications including in antifouling coatings for ship bottoms, metal molds and packaging.
The research regarding SLUGs will be presented at a meeting of the American Chemical Society, while a project to field test the effectiveness and durability of the substance on road signs is just beginning in northern Japan.
Source: American Chemical Society