By mimicking the structure of polar bear hair, the Zhejiang University team prepared an ultra-warm man-made fiber encapsulated with aerogel, which is warm, lightweight, and durable. On the 22nd, the results were published in the international journal Science.
The results were completed by the team of Professor Bai Hao from the School of Chemical Engineering and Biological Engineering and Associate Professor Gao Weiwei from the Department of Polymer Science and Engineering, Zhejiang University.
Bai Hao said that polar bears rely on super warm hair to adapt to the environment of minus 40 degrees Celsius. They found that polar bear fur is a hollow structure that encapsulates a large amount of "still" air, and each hair has a shell. Under an electron microscope, the shell is about 20 microns thick, accounting for nearly a quarter of the diameter of a hair.
The picture shows the polar bear fur under a light microscope. Courtesy of Zhejiang University).
Inspired by this discovery, the research team spent nearly six years preparing a novel "core-shell" structural fiber. At the center of the fiber is a polymer aerogel with long, small pores about 10 to 30 microns in diameter. The holes are arranged in the same direction, like a "warehouse" where air is stored. There is a TPU (thermoplastic polyurethane rubber) shell on the surface of the fibers that wraps the aerogel inside.
The nucleus is responsible for achieving super warmth, and by adjusting the direction and size of the pores inside the fibers, it is expected to 'lock' infrared radiation and prevent heat lossThe 'shell' is responsible for being strong and durable, providing good mechanical support for the fiber, making it resistant to wear, tensile and wash. Bai Hao said.
In order to verify the warmth effect, the researchers tried on and verified the warmth of down jackets, wool sweaters, cotton sweaters and "polar bear sweaters" at the same initial temperature in a constant temperature cold storage at minus 20 degrees Celsius. The less the surface temperature rises of the garment, the less heat is lost and the better the warmth of the garment.
The picture shows researchers testing the warmth of four garments: a "polar bear sweater", a down jacket, a woolen sweater, and a cotton sweater (from left to right) in a cold storage room at minus 20 degrees Celsius. Courtesy of Zhejiang University).
The researchers found that after a few minutes of testing, the surface temperature of the cotton sweater rose to 10At 8 degrees Celsius, the surface temperature of the down jacket rises to 38 degrees Celsius. The thickness is close to that of a woolen jacket, and the surface of the "polar bear sweater", which is only one-third to one-fifth of the thickness of the down jacket, rises to only 35 degrees Celsius.
Polar bear fur allows us to see how nature makes the 'core' and 'shell' each have their own functions, and the essence of biomimetic research is to learn from nature how to solve problems. Bai Hao said that by revealing the secrets of nature, discovering new knowledge, and creating new materials to improve people's lives is the mission of biomimetic research, and it is also the pursuit that the team has insisted on for many years. (Reporter Zhu Han).