Anyone with curly hair understands shape memory. No matter how much time you spend straightening your hair, as soon as it touches water the curls return because hair has shape memory. Harvard scientists have developed a new material that is similar to wool that has shaped memory and can change to a different shape in response to stimuli.
Shape memory has some interesting potential uses in textiles, such as a shirt with cooling vents that open when exposed to moisture and close when dry. Scientists at Harvard believe that such material could also design clothing that stretches or shrinks to a person’s measurements. The researchers developed a biocompatible material that can be 3D printed into any shape and pre-programmed with reversible shape memory.
The material uses a fibrous protein found in hair, nails, and shells known as keratin. The protein was extracted from leftover Agora wool used in textile manufacturing. One benefit of the research is that this material could help reduce waste produced by the fashion industry, one of the biggest polluters on the planet.
Keratin’s shape-changing capability comes from the hierarchical structure of the protein. A single chain is arranged into a spring-like structure called an alpha-helix. Two of the chains can twist together to create a form known as a coiled coil, with many of those assemble into protofilaments that eventually create large fibers.
The organization of the alpha helix and the connective chemical bonds give the material its strength and shape. The scientists created 3D printed keratin sheets in a variety of shapes. The permanent shape of the materials programmed using a solution of hydrogen peroxide and monosodium phosphate. Once the memory is set, the sheet could be reprogrammed and molded into new shapes. When exposed to water, the shape could be changed. However, when the material dried, it returns to its original shape.