New Fiber Inspired by Polar Bears Traps Heat as Efficiently as Down Feathers

Despite the extreme cold of the Arctic, polar bears can survive due to their super-insulating fur. A new fiber that imitates the porous hair of these bears has now been developed and humans may eventually benefit from it. Researchers have revealed that a sweater made from this fiber could have one-fifth of the thickness of a down coat but provide the same level of warmth, as published in the Science on Dec. 22.

Similar to polar bear hair, the new fiber has a core filled with thousands of pores, which are tiny pockets of air assisting in heat preservation. This core is encircled by a waterproof, flexible sheath. Unlike regular hair that is made from keratin, the core of this fiber is constructed from a synthetic material known as an aerogel.

Aerogels, which are ultralight, porous gels, act as excellent insulators. NASA employs them for rocket parts insulation, with the capability of withstanding severe heat. Nonetheless, the fragility of aerogels often restricts their application in textiles.

To build a more durable aerogel, a thread of aerogel made from chitosan, a polymer found in shellfish exoskeletons, was spun and frozen by materials scientist Hao Bai and his team. By freeze-drying the string and coating it with a flexible plastic termed thermoplastic polyurethane, the thread was strengthened. The finished fiber can carry up to 500 grams - approximately the weight of three billiard balls - and it can be dyed, washed, and knitted. It has a texture that falls somewhere between plastic and cotton, according to Bai, from Zhejiang University, Hangzhou, China.

Bai believes that the product could be made available to the general public soon, in addition to being used by specialized groups such as space agencies or the military.