The more clothing that you wear, the warmer you are … right? Well actually, scientists have developed a new textile that both warms wearers in cold environments, and cools them down when things heat up.
The experimental material was developed at China's Huazhong University of Science and Technology, by a team led by Prof. Guangming Tao. It's made by first freeze-spinning silk and chitosan, forming fibers with a porous microstructure – chitosan, incidentally, is a highly useful natural compound found in crustacean shells.
Next, the pores within the fibers are filled with polyethylene glycol (PEG), which is a phase-change material that takes the form of a liquid when warm, and a solid when cool. Finally, the fibers are coated with an organic polymer known as polydimethylsiloxane, to keep the PEG from leaking out while in its liquid state.
The resulting threads are said to be strong, flexible and water-repellent. They were tested by being woven together to form a patch of material, which was then sewn into a traditional polyester glove that was worn by a volunteer.
When that person placed their gloved hand in a chamber heated to 122 ºF (50 ºC), the PEG melted into a liquid – absorbing ambient heat as it did so – thus cooling the skin directly beneath the patch. Once the volunteer moved their hand into a chamber that had been cooled to 50 ºF (10 ºC), though, the PEG responded by solidifying and releasing the stored heat, warming their skin.
The scientists state that the fabrication process could be scaled up for large-scale production, and that integrating the material into the existing textile industry should be relatively easy.
A paper on the research was recently published in the journal ACS Applied Materials & Interfaces.
Source: American Chemical Society