Smart lining regulates temperature by changing shape from solid to liquid

Researchers at the University of Chicago have developed a chameleon-like building material:

changes its infrared color and quantitythe heat it absorbs or emits, depending on the external temperature. On hot days, the material emits up to 92% of its infrared heat, helping to cool the inside of the building. On cold days, by contrast, the material emits only 7% of its infrared radiation, keeping the building warm.

The principle of operation of the coating. Image: Hsu Group, University of Chicago's Pritzker School of Molecular Engineering

The secret of the material is in a special layer thatcan take two different forms: solid copper, which retains most of the infrared heat, or an aqueous solution, which emits infrared radiation. Switching between the two forms is achieved using a small discharge of electricity. This exposure causes a chemical shift between the states, either depositing copper in the form of a thin film or removing that copper.

The created material does not burn, and its color can bebe customized according to architectural needs. The aqueous phase is transparent and almost any color can be placed behind it without affecting its ability to absorb infrared radiation, the authors explain. They also note that the temperature at which the electrical source is activated and changes the properties of the coating can be adjusted by the user.

The material contains a layer that can taketwo states: solid copper, retaining most of the infrared heat, which helps keep the building warm; or an aqueous solution that emits infrared radiation, which can help cool the building. Image: Hsu Group, University of Chicago's Pritzker School of Molecular Engineering

In their work, engineers described a prototypecladding for the building: a square measuring about 6 cm in diameter. For real-world applications, large numbers of these heat-regulating sections can be combined into large sheets, like tiles. The study found that the material's ability to switch between two states remained effective even after 1,800 cycles.

In fact, we have found a low-energy waytreat the building like a person. You add a layer when you are cold and take off a layer when you are hot. Such a smart material allows us to maintain the temperature in the building without huge energy costs.

Po-Chun Hsu, professor at the University of Chicago and leader of the study

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