Polymer Springs Coil like a Cucumber Plant with Uv Light

Have you ever seen a cucumber plant hoist itself toward the sun? The power is in the plant's coiling tendrils. And now, those spiral structures have inspired researchers in Europe. They've developed a material that springs into action with a blast of UV light. Materials that move aren't new. The advance here is that these ribbons coil in different ways, depending on how they're cut from the source material. And different coils act differently under a UV lamp. They might wind more tightly, or unwind to their full length. Nathalie Katsonis, from the University of Twente in the Netherlands, and her lab teamed with Oxford University's Stephen Fletcher, to produce these chemical tendrils. They're made from liquid crystals, doped with a chiral molecule, to give the material a left-handed or right-handed twist. They also include a photoswitch-a molecule that changes its structure in response to light. A boatload of these tiny switches, acting together, triggers the coiling behavior. Now here's a tendril made from two different kinds of the ribbons. Combining them brings the researchers one step closer to a cucumber plant. The combo acts like a piston. It's stong enough, in fact, to ferry a tiny magnet back and forth. Look closely. The magnet on the material is dragging another magnet, below, along for the ride. This system isn't ready for practical applications yet. But microfluidic devices might use something similar in the future, Katsonis says, because the materials might drive valves without electrical wiring. Now that's a long climb from the cucumber patch. For Chemical & Engineering News, I'm Carmen Drahl.