We know that even hair that has been carefully straightened at high temperature will curl up when exposed to water. This is because the shape memory of the hair, that is, the material properties of the hair, allows it to change shape under certain stimuli and return to it under other stimuli. The original shape.
Inspired by this, the researchers turned their research objects to other materials, such as textiles. A promising idea about the shape memory of textiles is: a t-shirt that opens in a humid environment and closes when it is dry. It can be stretched to the size of a person. This also means that it will be a A dress that suits everyone.
Now, researchers at Harvard University have developed a biocompatible material that can be 3D printed into any shape and pre-programmed through reversible shape memory.
This material is made of keratin, a type of fibrin found in hair, nails and shells. From the point of view of molecular structure, the single strands of keratin are arranged into a spring-like structure called alpha helix. It is the alpha helix structure and the chemical bonds that give this material strength and shape memory.
In addition, the two strands of keratin are twisted together to form a structure called a spiral coil. Many of these crimped loops are assembled into raw filaments, which eventually form large fibers. When a particular fiber sheet is stretched or rearranged, the fibers are stretched into a stable structure. The fiber remains in this position until it is triggered to roll back to its original shape.
To prove this process, the researchers 3D printed keratin sheets of various shapes. They used hydrogen peroxide and monosodium phosphate solutions to program the permanent shape of the material-it always returns to its original shape when triggered. In addition, once the shape memory of keratin is set, it can be reprogrammed and shaped into a new shape.
For example, a keratin sheet is folded into a complex origami star as its permanent shape. Once the memory is established, the researchers immerse the star in water, and it will become plastic when it unfolds in the water.
The researchers envisioned some interesting uses for this new deformable material. They believe that the material can be used to make bras with customizable shapes and cup sizes, free-size t-shirts, or clothes with vents that can be opened according to moisture. In this way, the researchers hope that this will help solve the waste problem in the fashion industry.