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A new polymer-based paint that reflects almost all the sun's rays could help keep buildings, cars, planes and other structures exposed to the sun cool.
This polymer painting, described online September 27 Science, can be applied to various surfaces, including plastics, metals and wood. It could also be turned into recyclable tarpaulins to cover homes, cars or other enclosed spaces.
Materials scientist Yuan Yang of Columbia University and his colleagues made the heat-resistant paint using water, acetone and a polymer called polyvinylidene fluoride-co-hexafluoropropene. When the paint dries, evaporated acetone and water leave a polymer film filled with air pockets. These tiny cavities, ranging from hundreds of nanometers to several micrometers in diameter, reflect more than 96% of incoming sunlight. Other cold-roofed white paints helped to divert only 85% of the sunshine.
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The porous structure of the film also allows the heat absorbed by the material to escape into the air more easily than a sheet of solid polymer, says co-author of the study, Nanfang Yu, physicist applied to Columbia. During field trials, a coating of this polymeric paint under a clear sky in Phoenix remained at about 6 degrees Celsius cooler than the ambient air.
The use of paint to create heat shields could limit the use of energy-efficient air conditioning systems that often require polluting coolants, and offer protection against heat waves to people who do not have heat shields. no electricity (SN: 14/04/18, p. 18).
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