Traditional anti-icing surfaces are able to slow down and reduce ice accumulation, but are still susceptible to frosting over. Konrad Rykaczewski, assistant professor of Engineering at Arizona State University, has created an anti-icing coating that releases antifreeze liquid in response to surface icing, helping to reduce frost and ice build-up. Prof. Rykaczewski and his colleagues describe the innovation in the paper, “Bioinspired stimuli-responsive and antifreeze-secreting anti-Icing coatings.”
The coating is comprised of two layers: a superhydrophobic porous outer layer, and an inner layer infused with antifreeze (Fig. 1). The outer layer functions similarly to traditional anti-icing surfaces, where large water droplets effectively roll off the surface, preventing ice formation. However, in the event of frost, ice fills the pores of the outer layer and eventually makes contact with the antifreeze in the inner layer. This begins to melt the ice, and capillary pressure slowly drives the antifreeze up the walls of the pores. Eventually, antifreeze is secreted onto the outer layer, preventing frost build-up.
The outer layer is based on the non-adhesive characteristics of pitcher plant and lotus leaves, which traditional anti-icing surfaces are also modeled after. The leaves of these plants have microscale structures on their surfaces that enable water droplets to easily roll off the leaf. The “on-demand” release of antifreeze from the inner layer is based on the skin of the poison dart frog. The frog stores toxins in specialized glands in the inner layer of its skin, and when it senses danger, it releases the toxins through pores onto the outer layer.
Currently used methods of ice removal use either chemical, mechanical, or thermal techniques, or a combination. However, these methods are often time consuming, costly, and can impact the environment. Now in the prototype phase, Rykaczewski’s anti-icing coating uses 2-8 times less antifreeze and has been shown to delay icing up to ten times, compared to commercial methods.