Engineers at Stanford University have developed what they say is a low-cost, plastic-based textile that, if woven into clothing, could cool the body more efficiently than is possible with natural or synthetic fabrics. The researchers suggest that this family of fabrics could become the basis for garments that keep people cool without air conditioning.

“If you can cool the person rather than the building where they work or live, that will save energy,” says Yi Cui, associate professor of materials science and engineering.

To develop the cooling textile, the researchers blended nanotechnology, photonics and chemistry to give polyethylene—the clear, clingy plastic commonly used as kitchen wrap—characteristics desirable in clothing material: opacity to visible light and thermal radiation, air and water vapor permeability.

Researchers began with a sheet of polyethylene and modified it with a series of chemical treatments, resulting in a cooling fabric. Image credit: L.A. Cicero.They say the easiest attribute was allowing infrared radiation to pass through the material because this is a characteristic of ordinary polyethylene food wrap. But kitchen plastic is impervious to water and is see-through as well, rendering it less useful as clothing.

The researchers tackled these deficiencies one at a time.

First, they found a variant of polyethylene commonly used in battery making that has a nanostructure opaque to visible light but transparent to infrared radiation. This could let body heat escape and provided a base material that was opaque to visible light for the sake of modesty but thermally transparent for purposes of energy efficiency. They then treated the polyethylene with benign chemicals to enable water vapor molecules to evaporate through nanopores, allowing the plastic to breathe like a natural fiber.

That gave the researchers a single-sheet material that met their basic criteria for a cooling fabric. To make this material more fabric-like, they created a three-ply version: two sheets of treated polyethylene separated by a cotton mesh for strength and thickness.

To test the cooling ability of their three-ply construct versus that of a cotton fabric of comparable thickness, they placed a swatch of each material on a surface that was as warm as bare skin and measured how much heat each material trapped.

The comparison showed that the cotton fabric made the skin surface 3.6 degrees Fahrenheit warmer than their cooling textile. The researchers said this difference means that a person dressed in the new material might feel less inclined to turn on a fan or air conditioner.

The researchers are continuing their work on several fronts, including adding more colors, textures and cloth-like characteristics to their material.