A new shape-changing material promises to reduce the environmental footprint of the textile industry by production of a 3D-printed scaffold with diverse applications in bioengineering and smart textiles.

Harvard University, Sogang University (South Korea) and Korea Advanced Institute of Science and Technology (South Korea) researchers extracted keratin fibers from leftover wool materials to design a high-strength shape-memory material that is biocompatible and processable through fiber spinning and 3D printing. The programmable material can be bent out of shape in response to stimuli and bounce right back to its original form.

Twisting the helically shaped protein fibers together forms coiled coils that can be assembled into The smart textile was used to design a shape-shifting origami star. Source: Harvard Universityprotofilaments and larger fiber structures with shape memory characteristics. As the material is stretched, the coils unfurl and new bonds are formed that create stable sheets. The material remains in this state until exposed to stimuli that returns the coils back to their original shape.

Keratin sheets of differing shapes were 3D printed and programmed to return to a given state by treating the material with a solution of hydrogen peroxide and monosodium phosphate. The materials can then be molded into other shapes on a temporary basis in response to different stimuli.

The researchers demonstrated the shape-shifting material by folding a keratin sheet into an origami star as its permanent shape. When immersed in water, the sheet unfolded and became malleable enough to be rolled into and dried as a functional tube. The tube unrolls and resumes its original star shape when returned to a water bath.

This self-assembly process can be tuned to create materials from recycled wool with desired anisotropic structuring and responsiveness.