Scientists from China’s Zhejiang University and Westlake University have created a jacket out of an experimental, reversible fabric that can both heat and cool the wearer. The multilayered “Janus textile” consists of a base of expanded polytetrafluoroethylene (ePTFE) polymer fibers. When a garment made from the material is worn with the warming side facing outwards, zinc and copper nanoparticles on that side absorb solar energy and reduce the amount of body heat that escapes. When the wearer turns the garment inside out, a porous coating of polymethyl methacrylate (PMMA) polymer on the cooling side reflects the sunlight and helps dissipate body heat. According to the scientists, the textile is easy and inexpensive to manufacture, and it offers a breathability similar to that of cotton. A paper on the study, which is being led by Zhejiang University’s Qiang Li and Westlake University’s Min Qiu, was published in the journal Nano Letters.