Everyday Scientist

bending polymers with light

May 8, 2006 at 9:29 pm | sam | literature, nerd

Here’s a really cool paper in Nature, published back in 2003. The researchers use a polymer that contains azobenzenes, which isomerize upon irradiation of light. Here are some structures of the molecules they were using.

The researchers first formed a liquid-crystal array of molecule 1, then used crosslinking molecule 2 to polymerize the film. The cool part about this proceedure is that it aligns domains of the molecules; then, when illuminated by plane-polarized UV light, only molecules aligned in that direction photoisomerize and contract. When this happens, the entire film bends. If you then shine yellow light on the bent film, it goes back to flat. And then you can repeat bending and unbending an indefinite number of times! Check it out:

Cool, eh? If you have access to Nature.com, you can watch some real-time movies of the process. (In fact, I feel like I’ve seen these movies before, maybe back in 2003.)

I think we could make some really cool clothes with this material. Just imagine a visor than unfirls when it’s sunny or sleaves that roll up when you’re outside. Actually, those ideas are pretty stupid. How about a dress that flies up when you’re in the sun?

OK, I can’t think of any useful applications of this discovery. But someone will. And it’s cool looking.