When your chewing gum goes from wad to bubble, it becomes more transparent as it stretches. Pursuing similar logic, researchers at MIT have started predicting the amount of light that would pass through a polymer material, PDMS (Polydimethylsiloxane), based on its thickness and degree of stretch, and they want to use the equation they came up with and the polymer structure they used to design inexpensive smart windows that adjust the amount of light streaming in.
“For buildings and windows that automatically react to light, you don’t have to spend as much on heating and air conditioning,” Francisco López Jiménez, a postdoc in MIT’s Department of Civil and Environmental Engineering, tells MIT News. “The problem is, these materials are too expensive to produce for every window in a building. Our idea was to look for a simpler and cheaper way to let through more or less light, by stretching a very simple material: a transparent polymer that is readily available.”
In the future, a building’s windows could have layers of the polymer structure and become more or less transparent, thereby altering the amount of sunlight passing through, López Jiménez says.
Smart windows are currently very expensive — they’re found on the Ferrari 575M Superamerica, if that gives you a clue. Researchers at the University of Texas at Austin’s McKetta Department of Chemical Engineering are also working on making smart windows cheaper. Professor Delia Milliron’s team developed an electrochromic material that blocks 90 percent of near-infrared rays and 80 percent of the sun’s visible light, but not necessarily at the same time. You could block both to shut out heat and light or just opt for “cool mode” and still let the light shine in. Treating it like a regular window lets in both ultraviolet and near-infrared. The team has created a startup, Heliotrope Technologies, to try to get a product on the market.
While Heliotrope’s version of smart glass would require electricity to make the switch, the polymer MIT uses does not. In either case, the transition could be initiated either automatically or by the flip of a switch or timer.