A Chemical Solution to Defrosting Winter Windshields
Marie Donlon | July 11, 2017Boreyko, along with undergraduate students William McClintic and Kevin Murphy, experimented by treating aluminum plates to render them superhydrophobic—that is, so water-repellent that droplets easily roll off without sticking to the surface. Image credit: Virginia Tech In search of a faster way to defrost his car windshield on a cold winter morning, Jonathan Boreyko, assistant professor in the Department of Biomedical Engineering and Mechanics in the Virginia Tech College of Engineering, created a simple recipe for speeding up the process by 10 times.
Working with a team of undergraduate students, Boreyko chemically treated aluminum plates to make it so that droplets of water would effortlessly roll off (making them superhydrophobic). Once chilled, the frost that formed on the aluminum plate was in a “suspended state.”
"In other words, there were a lot of nano-air-pockets between the frost sheet and the actual solid substrate of aluminum,“ said Boreyko. "This made the frost highly mobile and easy to shed as it melted, kind of like a puck on an air hockey table."
Applying heat to an untreated surface typically results in the meltwater from the frost sticking to the surface, which requires slow evaporation to remove. Conversely, the frost quickly slides off of the treated surface in the form of slush (before the ice has even melted), resulting in a dry surface.
"My idea came from the realization that frost is simply dew droplets that have frozen over into ice — so if dew droplets can be highly mobile on a superhydrophobic surface, maybe frost can be too," Boreyko said. "Sure enough, when frost formed on our chilled superhydrophobic aluminum, the ice was able to trap air pockets underneath itself just like with liquid water."
Boreyko imagines the chemical mixture will have a number of applications, including on heat pumps, wind turbines and airplanes.
The research is published in ACS Applied Materials and Interfaces.