New Material: New Fiber Mimicking Polar Bear Pore Hair Keeps Warm Like Down

The extreme cold of the Arctic cannot match the super insulated fur of polar bears. Humans may one day benefit from similar materials, thanks to a new fiber that mimics the porous hair of bears. Researchers reported in the December 22 issue of Science that sweaters woven from this fiber are about one-fifth the thickness of down jackets, but they are also warm.

Like polar bear hair, the core of this fiber is filled with thousands of holes -- tiny air pockets that help prevent heat loss-- It is surrounded by a flexible and waterproof shell. But unlike hair made of keratin, its core is made of a synthetic material called aerogel.

Aerogels are lightweight, porous gels and excellent thermal insulation materials. NASA uses them to insulate rocket components, which can withstand extreme heat (SN: 2/14/19)。 However, aerogels are often fragile, which hinders their use in textiles.

The structure of polar bear fur (microscopic image shows on the left) inspired the design of new aerogel fiber (right)

In order to create a more robust aerogel, materials scientist Hao Bai and his colleagues spun and frozen an aerogel thread made of chitin, a polymer that exists in the exoskeleton of shellfish. The strings are freeze-dried and coated with a flexible plastic called thermoplastic polyurethane to increase the strength. The resulting fiber can carry 500 grams, about the weight of three billiards. And it can be woven, dyed and washed. Bai, a professor at Zhejiang University in Hangzhou, China, said that the texture of this fiber is between plastic and cotton.

"I think it can become a product for the general public in the near future, except for some special groups," such as the military or space agencies, Bai said.