The days of having to take your sweater on and off might be over very soon. Sure, there may have already been the occasional promise of high-tech thermal regulating gloves and hats here and there, but until now there has never been a fabric that actually changes its insulating properties based on its environment. That is exactly the kind of fabric that the University of Maryland researchers have created.
Their fabric allows more heat to pass through it in warm, moist conditions (like those of a sweaty body) and it stops heat from escaping in cooler, dryer conditions. The string holds the secret to the fabrics behavior. What’s so special about this string? The yarn is made from two different synthetic materials coated with carbon nanotubes.
One of the two materials absorbs water while the other repels it. Because of this, the fabric warps when it comes in contact with water, such as sweat. When this happens, it helps to open the fabric’s pores while also bringing the carbon nanotube coating closer together. In this way, the fabric automatically regulates the amount of heat that passes through it depending on conditions.
So, when conditions are warm and moist, the fabric allows infrared radiation (radiant heat) to pass through. In other words, your body’s heat can escape. But then when conditions become cooler and drier, the fabric closes back up again, reducing the heat that escapes. This keeps your body heat trapped beneath the sweater to keep you warm.
As you can see, the focus of this new technology is the fact that infrared radiation is a primary way the body releases heat. They have used this to their advantage in creating this ingenious material. The detailed description of the fabric and how it works had been published in the journal Science.
Min Ouyang, a professor of physics at UMD, said:
“The human body is a perfect radiator. It gives off heat quickly. For all of history, the only way to regulate the radiator has been to take clothes off or put clothes on. But this fabric is a true bidirectional regulator.”
YuHuang Wang, a UMD professor of chemistry and biochemistry and one of the paper’s corresponding authors, said:
“This is the first technology that allows us to dynamically gate [regulate] infrared radiation.”
This carbon nanotube coating is a special class of lightweight, carbon-based, conductive metal that gets activated when the yarn compacts. When it does that, it changes the way the fabric interacts with infrared radiation to allow more heat. This action is what they refer to as “gating” of infrared radiation. Gating is the string behaving like a tunable blind to transmit or block heat.
Depending on the tuning, the fabric either blocks infrared radiation or allows it to pass through. Wang explains:
“You can think of this coupling effect like the bending of a radio antenna to change the wavelength or frequency it resonates with. It’s a very simplified way to think of it, but imagine bringing two antennae close together to regulate the kind of electromagnetic wave they pick up. When the fibers are brought closer together, the radiation they interact with changes. In clothing, that means the fabric interacts with the heat radiating from the human body.”
Ouyang is very excited to be able to apply this gating phenomenon to the development of a textile that has the ability to improve the functionality of clothing and other fabrics. Meanwhile, others are very impressed by the idea. For example, Ray Baughman, a professor of chemistry at the University of Texas who was not involved in the study, said:
“This pioneering work provides an exciting new switchable characteristic for comfort-adjusting clothing. Textiles were known that increase porosity in response to sweat or increasing temperature, as well as textiles that transmit the infrared radiation associated with body temperatures. However, no one before had found a way to switch both the porosity and infrared transparency of a textile so as to provide increased comfort in response to environmental conditions.”
They still have a few things to work on before the fabric can be available to the public. Though they say the process to produce it is fairly easy and the materials used for the base fiber are readily available and the carbon coating can be easily added during a standard dyeing process. When this fabric does finally grace us with its presence, nobody will have to argue over the temperature of the air conditioning (or heating) anymore!