Plant-Based Film: Cooling
Image above links to website for Dr. Qingchen Shen at Cambridge
Journalist Adele Peters, writing in Fast Company, shares news of a new iridescent, plant-based film that offers both heat reflective properties and color. Many of us have heard of the whitest white paint, (link to another Fast Co article about the paint) which is being deployed to reflect heat from your roof into space.
From Ms. Peters’ article: “The usual way to generate a color is dye, but dye will absorb light and heat up, and that counteracts the cooling effect,” says Qingchen Shen, a postdoctoral researcher at Cambridge working on the material who presented the research at a recent meeting of the American Chemical Society. Since colors normally make surfaces hotter, most coatings designed for cooling are white. Instead of using dye, the team turned to structural color, the same phenomenon that makes soap bubbles or beetle shells appear iridescent. Light hits tiny structures on the surface and bounces around, reflecting different wavelengths from different angles to create shimmering colors.
A square meter of the film can generate over 120 watts of cooling power, as much as some air conditioners.
The end product should be affordable. “We wanted to make it cheap,” says Shen. “That’s why we used cellulose-based materials. Cellulose nanocrystals can be extracted from wood or cotton. Cellulose is the most abundant polymer in nature.”