Ever gotten off track working on origami (who hasn't?), and wished you could figure out how to undo your last few folds? There's a clever new material that might be able to help. It can revert to literally hundreds of earlier shapes by memory. Shape memory polymers — materials that "remember" their original form and return to it under certain conditions, such as changes in temperature — are cropping up everywhere these days. For instance, we recently covered a graphene-based paper that twists and folds when heated with a laser, but relaxes its shape when cooled off. But in the past, shape memory materials have only been able to revert to one or two fixed blueprints. Engineers would build the shape memory into the molecular structure, and it couldn't be altered.
Until now. Materials scientists at Zhejiang University in Hangzhou have just taken the shape memory game to a new level, by developing a carbon crosslinked polymer composed of polycaprolactone, or PCL. At temperatures below 70C, the material is elastic, meaning it can be temporarily deformed. As soon as it warms up again, it will revert to its shape memory. But crank up the heat too much (to above 130C) and the memory itself can be changed.
Flat memory polymer sheet folds into an origami bird under infrared heating Image Credit: Qian Zhao and Tao Xie
In essence, this means that you could make multiple, sequential changes to the material's shape, and "save" your progress every step of the way. Laboratory tests show that the material can snap between different shapes hundreds of times without showing signs of fatigue.
The researchers, who describe their material in last week's Science Advances, suggest that it might be used to build specialised medical devices or shapeshifting electronics. I'm personally holding out for somebody to bring a low cost, origami-grade version to market.
Top: Some complicated looking origami things that I certainly didn't make. Image Credit: fdecomite / Flickr