Material May Offer Cheaper Alternative to Smart Windows

MIT scientists have come up with a theory to predict exactly how much light is transmitted through a material, given its thickness and degree of stretch. Using this theory, they accurately predicted the changing transparency of a rubber-like polymer structure as it was stretched like a spring and inflated like a balloon. The researchers' experimental polymer structure and their predictive understanding of it may be useful in the design of cheaper materials for smart windows - surfaces that automatically adjust the amount of incoming light. The researchers envision covering window surfaces with several layers of the polymer structure. He says designers could use the group's equation to determine the amount of force to apply to a polymer layer to effectively tune the amount of incoming light.

Transcript

00:00:07 You may have noticed that as you stretch certain elastic materials the thinner they get, the more transparent they become. It's a simple enough concept to grasp, but to be able to predict mathematically exactly how much light will be trasmitted through a material, based on the amount of stretching, is a bit

00:00:22 more complicated. Now, MIT scientists have come up with a theory to predict exactly how much light is transmitted through a material given its thickness, initial transparency, and degree of mechanical deformation. They used PDMS, a rubbery transparent polymer, dyed with

00:00:39 various colors, a simple platform to secure the PDMS in place and air-filled syringes to inflate the material. Using this setup the researchers inflated the material to stretch it and allow light to shine through. With no deformation the structure appears opaque, but as it is inflated the material

00:00:55 lets in more light, at exactly the intensities predicted by their mathematical theory. The researchers say their experimental polymer structure and their predictive understanding of it may be used in the design for smart windows, which are surfaces that automatically adjust the amount of incomming

00:01:12 light.