Chinese scholars prepare polar bear hair bionic thermal insulation material

By imitating the structure of polar bear hair, a team from Zhejiang University prepared an ultra-warm artificial fiber encapsulated with aerogel. This material is warm, lightweight and durable at the same time. On December 22, 2023, a paper related to this achievement was published in the international journal "Science".

The achievement was completed by a team of Professor Bo Hao from the School of Chemical Engineering and Bioengineering and Associate Professor Gao Weiwei from the Department of Polymer Science and Engineering at Zhejiang University.

Bai Hao said that polar bears rely on their super warm hair to adapt to the environment of minus 40 degrees Celsius. They found that polar bear hair is a hollow structure that encapsulates a large amount of "still" air, and each hair has a shell. Under an electron microscope, this shell is about 20 microns thick, accounting for nearly a quarter of the diameter of the hair.

Inspired by this discovery, the research team spent nearly 6 years preparing a new type of "core-shell" structural fiber. The center of the fiber is a polymer aerogel, which is dotted with long pores with a diameter of about 10 to 30 microns. The small holes are arranged in the same direction, like "warehouses" for storing air. There is a TPU (thermoplastic polyurethane rubber) shell on the surface of the fiber to wrap the aerogel inside.

"The 'core' is responsible for achieving super warmth. By regulating the direction and size of the small holes inside the fiber, it is expected to 'lock' infrared radiation and prevent heat loss; the 'shell' is responsible for being strong and durable, providing good mechanical support for the fiber. , making it wear-resistant, stretch-resistant and washable," said Bohao.

In order to verify the thermal insulation effect, the researchers tried to verify the thermal insulation effect of down jackets, woolen sweaters, cotton sweaters and "polar bear sweaters" with the same initial temperature in a constant temperature cold storage of minus 20 degrees Celsius. The less the surface temperature of clothing rises, the less heat is lost from the human body and the better the clothing's thermal performance.

The researchers found that after a few minutes of testing, the surface temperature of the cotton sweater rose to 10.8 degrees Celsius, and the surface temperature of the down jacket rose to 3.8 degrees Celsius. The surface of the "polar bear sweater", which is close to the thickness of a woolen sweater and only one-third to one-fifth of the thickness of a down jacket, only rises to 3.5 degrees Celsius.

"Polar bear hair allows us to see how nature allows the 'core' and 'shell' to perform their respective duties. The essence of bionic research is to learn from nature how to solve problems." Bohao said that by revealing the secrets of nature, Discovering new knowledge and creating new materials that improve people's lives is the mission of bionic research, and it is also the pursuit that the team has persisted in for many years.