Imagine being able to snap your fingers and change metal on command. Rice University researchers are getting closer to that dream with their latest creation.
Materials engineers Rafael Verduzco and graduate student Morgan Barnes created a material that shapeshifts in both ambient conditions and morphs again when heat is applied. The material’s morphing power also works in reverse.
How the material shapeshifts
The process works on a nano level. Liquid crystals and the elastomer holding them fight for control, the researchers explained.
When the material is cooled, the shape programmed into the crystals wins out. When heat is applied, the crystals relax and the elastomer takes over. The team likened it to ice melting into water.
“These are made with two-step chemistry that has been done for a long time,” said Verduzco, a professor of chemical and biomolecular engineering and of materials science and nanoengineering.
“People have focused on patterning liquid crystals, but they hadn’t thought about how these two networks interact with each other.
“We thought if we could optimize the balance between the networks – make them not too stiff and not too soft – we could get these sophisticated shape changes.”
Barnes and Verduzco really did create some sophisticated shapes. Rather than use standard cubes or spheres or pyramids, the duo built out faces, their university logo, a rose, and a lego block.
When heated to 80 degrees Celsius (176 degrees Fahrenheit), the complex structure collapses into a flat sheet. Upon cooling, the shape takes only minutes to reform.
“Instead of simple uniaxial shape changes, where you have something that lengthens and contracts, we’re able to have something that goes from a 2D shape to a 3D shape, or from one 3D shape to another 3D shape,” Barnes said.
Modern applications for this shape-shifting material
Not only does this research lead to entrancing shape changes, but the researchers say it can be used for more innovative purposes.
The material could help soft robotics in rescue and research teams flatten and reach hard-to-find areas. It could also be used in biomedical robotics that needs materials to take pre-programmed shapes at someone’s body temperature.
Barnes said the lab’s next major step is to lower the activation temperature so the material could be used in biomedical robotics.
“Activation at body temperature opens us up to a lot more applications,” she explained.
She’d also like to develop a variant that reacts to light rather than heat. “We want to make it photo-responsive,” Barnes said.
“Instead of heating the entire sample, you can activate only the part of the liquid crystal elastomer you want to control. That would be a much easier way to control a soft robot.”
The research was published in a recent edition of the Royal Society of Chemistry’s journal Soft Matter.