New Material: Shape Memory Polymers

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Ever strayed astray in an origami process (who hasn’t?), and wished you could figure out and recreate your previous steps? Now a new “smart” material might help. It can restore hundreds of previous shapes through its own memory ability.

Shape memory polymers – materials that can “remember” their original shape and return to them under certain conditions, such as a certain temperature – are gaining traction in a variety of fields. For example, there have been reports in the media of a graphene-based paper that can bend and wrinkle under laser heating, and recover its shape after cooling. However, the shape memory of the material is only there once or twice. Engineers can only build a material’s memory of its shape on the molecular structure, which cannot be changed again afterwards.

Now, materials scientists at Zhejiang University have taken the shape memory game to the next level by developing a carbon-crosslinked polymer composed of polycaprolactone. Below 70 degrees, the material is elastic, meaning it can be temporarily deformed. And when it is heated up again rapidly, it will restore its shape memory. But when the temperature rises too high (up to 130 degrees), the material’s own memory can be changed.

Steps in the transformation of carbon-crosslinked polymer materials from one structure to another

Essentially, this means that we can make multiple successive changes to the material shape and “save” each step in the process. Laboratory tests have shown that the material can be reshaped hundreds of times without showing signs of fatigue.

As for its application, the research team said it might be used to create a special kind of medical or shape-shifting electronic device.