For years now, scientists have marvelled at the insulating qualities of polar bear fur, suggesting that it could inspire manmade heat-retaining materials. Well, Chinese researchers have now developed just such a substance, which reportedly outperforms real fur.
One of the big secrets to polar bear fur's success lies in the fact that each hair is hollow. This characteristic minimizes their thermal conductivity, keeping them from drawing heat away from the animal's body. They're also very elastic, allowing them to stretch instead of breaking, plus they repel water.
A team at the University of Science and Technology of China set out to emulate these qualities, starting with tiny wires made of an element known as tellurium. After being coated in a layer of carbon, these nanowires were dissolved via a chemical process. What resulted was millions of hollow carbon tubes, not unlike polar bear hairs.
Those carbon tubes were subsequently wound together into a "spaghetti-like" arrangement, forming a small cube of insulating aerogel. When tested, that aerogel was found to be both lighter and more resistant to heat flow than other insulating materials. Additionally, it was highly hydrophobic (water-repellant), plus the tubes were even stretchier than hairs from the actual bears.
"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," says Prof. Shu-Hong Yu, co-senior author of a paper on the research. "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."
That said, tellurium is unfortunately quite rare and expensive, limiting the commercial viability of the technology in its current form. With that in mind, the scientists are now looking into utilizing template wires made from different, cheaper elements.
The paper was recently published in the journal Chem.
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