Imagine a material that can always return to its original shape no matter what stimuli you applied to it. Now, researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed just such a material and according to them, it has a wide range of applications from aerospace to fashion.
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The biocompatible material can be 3D-printed into any shape and further pre-programmed with reversible shape memory. Made with keratin extracted from leftover Agora wool used in textile manufacturing, the new material is also eco-conscious showing that fashion and other textile-related industries can be environmentally friendly.
"With this project, we have shown that not only can we recycle wool but we can build things out of the recycled wool that have never been imagined before,” said Kit Parker, the Tarr Family Professor of Bioengineering and Applied Physics at SEAS and senior author of the paper.
“The implications for the sustainability of natural resources are clear. With recycled keratin protein, we can do just as much, or more, than what has been done by shearing animals to date and, in doing so, reduce the environmental impact of the textile and fashion industry.”
To achieve their amazing memory, these new materials rely on keratin's hierarchical structure. Keratin is composed of spring-like structures known as alpha-helix that twist together to form a structure known as a coiled-coil.
When a fiber is altered by an external stimulus, the coiled-coils uncoil, allowing the fiber to remain in its new position until it is triggered to turn back into its original form. To test this theory, the researchers printed different materials with different memories.
One keratin sheet was printed as an origami star. When the star was dunked in water, it unfolded and became malleable enough to be transformed by the researchers into a tight tube.
It remained in its new shape even when dry. To get it back to its original shape, the researchers then put it back into water where it transformed back into a star. Now, that's an exciting development!