"Science" announces the first fabric that automatically adjusts temperature

Despite decades of research and innovation in high-tech functional fabrics, the development of a variety of moisture-absorbing breathable or warm fabrics for outdoor sportswear, but so far, has never changed its response to environmental changes Thermal properties of the material appear.

Recently, researchers at the University of Maryland in the United States have developed a fabric that automatically adjusts the heat through it. The results of the study were published in Science on February 8, 2019. The fabric allows the body's heat to escape when the ambient conditions are warm and humid, such as when sweating in large amounts in the summer. When the external environmental conditions become cool and dry, the fabric will help reduce the body's heat dissipation and keep warm.

The researchers made this fabric with functional yarns coated with conductive materials. In hot, humid conditions, the yarn bundle tightens and activates the coating, changing the way the fabric interacts with infrared radiation. They call this function a "gating" of infrared radiation, through which the heat of transmission can be adjusted by opening and closing the "door". This is the first time that infrared radiation has been controlled in a "dynamic door" manner.

The fibers from which the yarn is made consist of two different synthetic materials, one for water absorption and the other for hydrophobic. The surface of the yarn is coated with a carbon nanotube coating which is a special lightweight carbon based conductive material. Since the fibrous material is both water absorbing and hydrophobic, when it is exposed to a moist environment such as a sweaty body, the fibers are bent and deformed to tighten the yarn bundle. This causes the voids in the fabric to become large, changing the electromagnetic coupling between the carbon nanotubes in the coating while promoting heat dissipation.

This is an easy to understand way of action, and it is conceivable to bring the two antennas close together to adjust the electromagnetic waves they receive. Similarly, when two fibers are close together, the radiation between them changes. In clothing, it is reflected in the interaction of the fabric with the heat emitted by the human body.

Based on the conditioning effect, the fabric either blocks infrared radiation or allows infrared radiation to pass. The reaction is almost instantaneous, so before the people realize the heat, the clothes are automatically adjusted to cool down. Conversely, the dynamic door mechanism works in reverse to capture heat and keep the body warm.

This study demonstrates for the first time that textiles can regulate their heat exchange with the environment. According to the researchers, the fiber materials used in the textile are easily available, and the carbon coating is easily added during the standard dyeing process. Therefore, it is very important to apply this "gating" phenomenon to the development of functional textiles. The meaning.