Yanlin Song and his team at the Chinese Academy of Sciences in Beijing, China have replicated the formation of the leaf's exterior by spinning polymer into long hollow fibres contained within reflective films. The underside of the leaf is much better equipped to deflect light than the top, which only reflects light because of the tiny layer of hairs found on the underside of the leaf. This means less heat can get through or escape when the weather is cold. Should the weather change to more favourable conditions and temperatures, the leaf will flip itself over to reflect the light instead of absorbing it like it would do if the temperatures were lower. Most of the time, the leaves appear green but when they flip over to reflect the sun's rays, they turn a brilliant shade of white which is somewhat of a marvel to watch.
Song and the team found that by managing the film's thickness and making the fibres as accurate to the leaf's structure as they could, they could create the highly reflective properties seen with the original leaf. Each film was tested with a coating of diarylethene, which is a compound that goes from red to colourless when light is present and the structure from a closed ring to an open one. They discovered during testing that the coating stopped the compound from altering colour with the added benefit of repelling water.
After examining the structure of the roof coating, a leading surface science specialist declared the roof coatings were a suitable material for many building applications due to the reflecting nature of them, as well as their water-resistant features. A major environmental development will be improving the robustness of the fragile interfaces, but at present placing leaves onto the roofs of buildings would not prove to be a viable alternative.