Compound changing color on demand
Posted by evolvingwheel on October 22, 2007
Researchers from MIT have created a gel that changes color in response to external stimuli. The compound has the unique characteristic of changing colors when exposed to different kinds of stimuli – light, moisture, pressure, and possibly voltage. The versatile gel provides some significant signatures for changes in the surrounding environmental components.
The researchers have achieved this remarkable feature by using a copolymer thin film made of alternating layers of two materials, polystyrene and poly-2-vinyl-pyridine. The thickness of those layers and their refractive indices determine what color light will be reflected by the resulting gel. External stimuli produce changes to the thickness of the layers (space between them), which then alters the refractive indices of the layers and hence changes the color of the gel. As claimed by the researchers:
The key to manipulating the thickness of the poly-2-vinyl-pyridine (2VP) layer is to give the nitrogens on each segment of the 2VP block a positive charge, yielding a polyelectrolyte chain that can swell to more than 1,000 percent its volume in water.
This is a fundamental research breakthrough – an ingenious way of swelling ultra thin compunds/layers by sending a small chanrge through it. For more details, read the article [here].
I have been thinking of the commercial aspects of this research – and many others already have. True innovation in materials has the key to unfold areas of the application that could have never be contemplated earlier. Some of the immediate uses that comes to my mind are:
- Coumpound can be used to detect moisture in food warehouses – where dryness is essential.
- Small pressure changes can be detected with the presence of explosive materials.
- Color changes through a large spectrum of light can produce vivid and visible responses to the slightest change in the environmental factors.
- — I will do research and think of few more — any other ideas are more than welcome.
Picture: MIT News – Ned Thomas, Morris Cohen Professor of Materials Science and Engineering and head of the department, left, and Joseph Walish, graduate student in materials science and engineering.