Surviving the bitter cold Arctic winters isn’t easy, just ask the polar bears. On second thought, don’t do that. But they must have some secret that helps them live in subzero temperatures with no down jackets or space heaters. That secret happens to be in their hair, which engineers are now attempting to replicate with synthetic materials.
Materials scientists in China have developed an insulator that reproduces the structure of individual polar bear hairs, while scaling toward a material made up of many hairs for real-world applications in architecture and aerospace. Polar bear hairs are hollow, and the shapes and spacing of their hollow centers is responsible for their distinctive white coats, as well as being a source of incredible heat-holding capacity, water resistance, and stretchiness.
“Polar bear hair has been evolutionarily optimized to help prevent heat loss in cold and humid conditions, which makes it an excellent model for a synthetic heat insulator,” explains Shu-Hong Yu, a professor of chemistry at the University of Science and Technology of China (USTC) and co-senior author of the paper published in the journal Chem. “By making tube aerogel out of carbon tubes, we can design an analogous elastic and lightweight material that traps heat without degrading noticeably over its lifetime.”
In an effort to copy the structure of these hairs and scale it to a practical size, the research team manufactured millions of hollowed-out carbon tubes, each the size of a single strand of hair, and wound them into a spaghetti-like aerogel block.
The team found that the faux-polar bear hair tube design was lighter in weight and more resistant to heat flow compared to other aerogels and insulation components. It was also barely affected by water, which exhibits the principles that help keep polar bears warm while swimming. This synthetic material is also extremely stretchy, which could help with its engineering applicability.
The next challenge for researchers is to now scale up the manufacturing process from a centimeter scale to a meter scale. “While our carbon-tube material cannot easily be mass produced at the moment, we expect to overcome these size limitations as we work toward extreme aerospace applications,” says Yu.
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