The Arctic’s harsh cold is easily tackled by the remarkable insulating fur of polar bears. There’s potential for humans to harness a comparable material, thanks to a novel fiber mimicking the bears’ porous hairs. A study published in the December 22 issue of Science reveals that a sweater crafted from this fiber, despite being only about one-fifth the thickness of a down coat, offers similar warmth.
Similar to polar bear hair, the fiber comprises a core filled with numerous pores, acting as small air pockets that prevent heat from escaping. This core is encased in a flexible, waterproof sheath, distinguishing it from natural hair, which is composed of keratin. The core material itself is a synthetic aerogel, renowned for its ultralight and porous nature, making it an exceptional insulator. NASA has long employed aerogels to insulate rocket components, owing to their ability to withstand extreme temperatures. However, their fragility has limited their application in textiles.
In an effort to enhance the durability of aerogels, materials scientist Hao Bai and his team devised a method involving spinning and freezing a thread of aerogel derived from chitosan, a polymer sourced from shellfish exoskeletons. Subsequent freeze-drying of the thread and coating it with a pliable plastic known as thermoplastic polyurethane significantly increased its strength. The resulting fiber boasts impressive resilience, capable of supporting up to 500 grams, roughly equivalent to the weight of three billiard balls. Moreover, it can undergo knitting, dyeing, and washing processes. Bai describes the texture of the fiber as falling somewhere between that of plastic and cotton.
Bai envisions broad applications for this innovation, foreseeing its adoption not only by specialized groups like the military or space agencies but also by the general public in the near future.
