Smart material inspired by carnivorous plant rapidly changes shape in response to temperature and pH changes

Scientists in China have designed a smart material that rapidly switches from one shape to another just like a Venus flytrap plant snaps close when trapping prey.

Inspired by carnivorous plant’s movement, researchers have been designing polymers that rapidly change shape in response to external stimuli. However, the snapping process is usually irreversible, which has so far limited the materials’ practical potential.

Tao Xie and co-workers from Zhejiang University have now created a hydrogel-based system that is the first to undergo reversible snapping. The assembly comprises layers of three dissimilar hydrogels: a non-responsive, a thermo-responsive and a pH-responsive one, which are held together with a supramolecular glue. This allows the material to react to pH or temperature changes and switch between two shapes (eg convex and concave disk).

Xie and co-workers suggest that the rapid snapping mechanism could be extended to other shape-changing materials, such as shape memory polymers and liquid crystalline elastomers.