Graphene-based de-icing material upgraded

Rice University scientists have advanced their graphene-based de-icer to serve a dual purpose. The new material still melts ice from surfaces and wires when conditions get too cold, but ice won’t form at all down to temperatures of -14°C. The material can be spray-coated, making it suitable for large applications like aircraft, power lines, radar domes and ships.

Rice chemist, James Tour gave the de-icer superhydrophobic capabilities that passively prevent water from freezing down to -14°C. The tough film that forms when the de-icer is sprayed on a surface is made of atom-thin graphene nanoribbons that are conductive, so the material can also be heated with electricity to melt ice and snow in colder conditions.

"We've learned to make an ice-resistant material for milder conditions in which heating isn't even necessary, but having the option is useful," Tour said. "What we now have is a very thin, robust coating that can keep large areas free of ice and snow in a wide range of conditions."

The Rice films use graphene nanoribbons modified with a fluorine compound to enhance their hydrophobicity. They found that nanoribbons modified with longer perfluorinated chains resulted in films with a higher contact angle, suggesting that the films are tunable for particular conditions.

The researchers discovered that below -14°C, water would condense within the structure's pores, causing the surface to lose both its superhydrophobic and ice-phobic properties. At that point, applying at least 12V of electricity warmed it enough to retain its repellent properties.

Applying 40V to the film brought it to room temperature, even if the ambient temperature was -31°C. The researchers said that ice allowed to form at that temperature melted after 90s of resistive heating.

According to the researchers, while effective, the de-icing mode did not remove water completely, as some remained trapped in the pores between linked nanoribbon bundles. Adding a lubricant with a melting point of -51°C to the film made the surface slippery, sped de-icing and saved energy.

Author
Tom Austin-Morgan

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