IMAGINE a single garment that could adapt to changing weather conditions, keeping its wearer cool in the heat of midday but warm when an evening storm blows in.
Researchers said this outdoor and indoor wear could drastically reduce the need for air conditioning (during summer) or heat (during winter).
The American Chemical Society said researchers have made a strong, comfortable fabric that heats and cools skin, with no energy input.
Researchers use freeze-spun silk and chitosan, a material from the hard outer skeleton of shellfish, into colored fibers with porous microstructures. They filled the pores with polyethylene glycol (PEG), a phase-changing polymer that absorbs and releases thermal energy. Then, they coated the threads with polydimethylsiloxane to keep the liquid PEG from leaking out.
The resulting fibers were strong, flexible and water-repellent. To test the fibers, the researchers wove them into a patch of fabric that they put into a polyester glove.
When a person wearing the glove placed his hand in a hot chamber (122 F), the solid PEG absorbed heat from the environment, melting into a liquid and cooling the skin under the patch. Then, when the gloved hand moved to a cold (50 F) chamber, the PEG solidified, releasing heat and warming the skin.
The process for making the fabric is compatible with the existing textile industry and could be scaled up for mass production, the researchers say.