Novel material offers cheap alternative to smart windows

A new rubber-like polymer structure may be useful in designing of cheaper materials for smart windows -- surfaces that automatically adjust the amount of incoming light, say researchers including one of Indian-origin.

For buildings and windows that automatically react to light, you do not have to spend as much on heating and air conditioning.

"The problem is that these materials are too expensive to produce for every window in a building. Our idea was to look for a cheaper way to let through more or less light, by stretching a transparent polymer that is readily available," explained Lopez Jimenez, researcher at Massachusetts Institute of Technology (MIT).

The research team included Shanmugam Kumar from the Masdar Institute of Science and Technology in Abu Dhabi and Pedro Reis, professor of civil and environmental engineering and mechanical engineering.

The team analysed the light-transmitting properties of a simple block of PDMS -- a widely used rubbery, transparent polymer.

The polymer block contained some darkened regions, and the team was looking to see how deforming the block would change the light traveling through the material.

"It was a happy accident. We were just playing with the material, and we soon got interested in how we can predict this and get the numbers right," Jimenez said in a paper published in the journal Advanced Optical Materials.

After following some more experiments, the researchers were able to come up with the new material.

"If you give me the initial material properties and measure the incoming light intensity, we know exactly how much light will go through with deformation," Jimenez noted.

Jimenez envisions covering window surfaces with several layers of the polymer structure. The 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.