Untethered Shape-changing elastomer via liquid-gas phase transition

We present a new system capable of untethered shape-morphing, using an elastomer-alcohol composite capable of large expansion when heated.
The liquid-gas transition of alcohol droplets dispersed in a silicon elastomer matrix is used to design reversible shape-changing materials. Upon heating, the liquid boils inside the cavities, leading to a rise of the inner pressure and to an uniform expansion of the material¹. Our goal is to design planar sheets that can evolve to controlled 3D shapes using programmed in-plane metric deformation. The strategy adopted here is to use an embedded structure, a network of small thin branches cut out of a mylar sheet, to geometrically constrain the deformations of the material. Meshes are designed to locally allow deformation only along some selected directions. We report the different patterns used for the mesh, such as oriented chevrons or diamond shapes, and how the variation of the meshes parameters (density, angle, orientation) can impact the deformation of the object. We finally demonstrate that the choice of different meshes enables one to design basic 3D shapes.

¹Miriyev A., Stack K., & Lipson H. (2017) Soft material for soft actuators. Nature communications.