Inspenet, April 23, 2023
Scientists at the University of Cambridge have developed a plant-based iridescent coating that cools when exposed to sunlight. An innovation that could reduce the need for air conditioning in homes, buildings and vehicles, with a positive impact on the environment.
Researchers recently developed an ultra-white paint that can keep things cooler, and now Cambridge University scientists are turning to nature-inspired cellulose nanomaterials that would create self-cooling, iridescent houses.
“The usual way to generate a color is dye, but the dye absorbs light and heats up, which counteracts the cooling effect,” said Qingchen Shen, a Cambridge postdoctoral researcher working on the material and presenting the research at a meeting. recent from the American Chemical Society.
The coating is a thin nanostructured film made of cellulose
Since colors tend to warm surfaces more, most coatings designed to cool are white. Instead of using dyes, the team turned to structural color, the same phenomenon that makes soap bubbles or beetle shells appear iridescent. Light strikes small surface structures and bounces back, reflecting different wavelengths from different angles to create brilliant colours.
However, as Shen explains, color generally absorbs heat, rather than reflects it, but his invention of a thin nanostructured film made of cellulose under a thin layer of white was able to generate more than 120 watts of cooling power, much like some air conditioners.
“We wanted it to be cheap,” Shen added. “That’s why we use cellulose-based materials. Cellulose nanocrystals can be extracted from wood or cotton. Cellulose is the most abundant polymer in nature.”
In one study , the material was 7.2 degrees Fahrenheit cooler (or 4 degrees Celsius) than the surrounding air during the day. At night it was almost 20 degrees Fahrenheit colder. Pasted on walls or roofs, the material could significantly help cool the interior of the house and greatly reduce electricity consumption.
Photos : University of Cambridge
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