Last year, Purdue University engineers used their expertise in materials science to produce The whitest color in the world, has the ability to reflect approximately 98% of sunlight, thereby offering great potential for increased energy efficiency. The team has now perfected the formula and created a thinner, lighter version that they say is suitable for use in cars, trains and planes.

The original version of Ultra White owes its superior ability to reflect sunlight to the addition of barium sulfate, a chemical compound used in photographic paper and cosmetics. It was added to the mixture in the form of particles of different sizes with different ability to scatter light, which allowed the paint to reflect a larger part of the spectrum of sunlight.

With a reflectance of 98.1%, the material significantly exceeds the reflectance of commercially available heat reflective paints, which range from 80 to 90%. In tests on exterior surfaces, the team found that the paint can significantly reduce their temperature compared to the surrounding environment, with cooling effects comparable to conventional air conditioners.

To achieve this level of radiative cooling below ambient temperature, the team had to apply a paint layer at least 400 microns thick. This was applicable to large stationary structures such as the roof of a building. But for applications that require precise size and weight, the paint must be thinner and lighter.

The new material now contains boron nitride in the form of hexagonal nanowires and offers 97.9% solar reflectance, slightly lower than the original material, but possible with layers 150 microns thick. The new paint is not only lighter, but also less dense, so it weighs about 80% less. The scientists have filed patents for the technology and are now negotiating the commercialization of their paint. The research was published in časopise Cell Physical Science Reports.

Source: newatlas.com.

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