Slippery coating keeps frost out of the environment while being kind to it

Let’s start with “A Song of Ice and Fire” before we get into formulas and formulations. This sequence is adapted from George R. R. Martin’s novels of the name. It’s part of HBO’s water-cooler series “Game of Thrones.”

Jon Snow and his brother band venture on a winter retreat to hunt wights. They risk the national security of Westeros and are trapped in a polar vortex by the Night King’s army. Daenerys Targaryen is Jon’s aunt and dragon mom. She arrives at the venue with her fiery dragons ex Machina.

The following is an antiseptic battle of the living and the deceased. Dany’s dragons set fire to the marching freezing front with a signature move full of fire and fury. The Night King uses an ice spear with Olympic-style precision to kill one of Dany’s dragons as she prepares for her departure. In a dramatic twist of events, all Night King-esque, the fiery beast is transformed into a frost-breathing, ice dragon to spread winter faster. Frosting and icing have been a problem for centuries, be it in North America or the mythical North of the Wall.

Winter is a time when nature blankets the surrounding areas in a white blanket. It’s incredibly diverse, but infinitely monochromatic. There’s more to this beautiful icy beauty. The threat of frost formation or ice on functional surfaces can cause economic losses of billions of dollar across various industries.

The freezing of supercooled water droplets on aircraft wings can lead to heavy ice accumulation, which alters the in-flight aerodynamics. This can pose a serious threat to its operational safety. Icing is responsible for 9.5% of all fatal accidents in aircraft. The most tragic was the 1985 crash of Arrow Air Flight 1285, which killed 256 people. Frosting and icing also affect wind turbines, thermal control systems, building infrastructure and telecommunications systems.

Over the years, significant efforts have been made to develop engineered surfaces that are resistant to ice formation or have low adhesion to the surface. Most of the conventional methods to prevent surface icing during cold winters rely heavily upon liquid deicing chemicals, which can be applied in thousands of gal. They are liquid and can be quickly dissolved or depleted so it is necessary to reapply them frequently. It is evident that it has a significant impact upon the environment and economy.

What about using materials that can withstand frost for hours and are solid when they are cold? My latest research paper at the University of Illinois Chicago addresses this burning issue. We have created a large library of bio-friendly phase change materials (PCM)-based formulations. These materials have a melting temperature higher than water’s freezing point. They can be kept in a solid state far from condensing droplets, but switch to liquid in their immediate vicinity. This happens by trapping latent heat from condensation and preventing drops from freezing for a longer time.

To put it another way, the very humid environment that can summon the cold army of frost may be used to stop it. Functional coatings made from these PCMs work on the principle of leveraging thermoresponsive qualities, which can generate an in situ slippery surface layer. The self-lubricating liquid layer acts as a barrier between underlying substrate and a variety foulants. These foulants can range from ice to bacteria, making it difficult for them to establish a strong foothold. The coatings offer exceptional frost resistance as well as optical transparency under extreme environmental precipitation such an icestorm and high shear flow stability in abrasive environments. They also have self-repairing properties if mechanically damaged. This diverse portfolio of functionalities is integrated into one material system. We expect the developed compositions to be widely used in the energy, transport, healthcare, and military sectors.

This story is part Science X Dialog. Researchers can share their findings from published research articles. This page provides information about ScienceX Dialog, as well as how to get involved.

More information:
Rukmava Chatterjee and co., A Family of FrostResistant Coatings. Advanced Materials (2022). DOI: 10.1002/adma.202109930

Rukmava Chatterjee, a Ph.D. student in the University of Illinois Chicago, has industrial-academic experience (10+ year) in thermal management and material science & design. She is trained to solve difficult scientific problems.