A Cool New Covering | weatherology°
By: Meteorologist Michael Karow
Updated: Aug 4th 2020

A Cool New Covering

Now here is a scientific discovery that is very timely as we work through what is often the hottest part of the year, in the Northern Hemisphere. Researchers in China have manufactured a new fabric that excels in three major criteria for keeping the body cool. It not only effectively transfers heat away from the body, but also is breathable and water repellent, all while being relatively easy to manufacture.

The new fabric doesn't yet have a catchy name. It is composed of the polymers, polyurethane and fluorinated polyurethane, along with a thermally conductive filler called boron nitride. The process to manufacture this fabric is called electrospinning, which involves applying high voltage to the polymers in solution as they are pushed out of a syringe. As they exit the syringe, they form a network of fibers which are coated with the boron nitride. The pores between the network of fibers are what give the fabric its breathability, allowing sweat to evaporate and air to circulate. The chemical makeup of the fluorinated polyurethane is what gives the fabric its ability to repel water. Finally, the boron nitride, which coats the network of fibers, provides the thermal conductivity needed to transfer heat away from the body.

In tests of its water repellency, drops of water that were applied to the material bounced several times on its surface before finally resting, but not sticking, to the fabric. In another test, of its breathability, a sample of the fabric was placed in between two chambers, one filled with air underneath another filled with water. As the pressure was increased in the lower chamber, air bubbled through the fabric, but didn't allow water to fall through, demonstrating the fabric's breathability and degree of waterproofing. Finally, to demonstrate the degree to which the new material can transfer heat, samples of the substance both with and without the boron nitride filler were placed on a heater. The samples with the boron nitride, were measured at 6°C (10.8°F) warmer than those without the filler, indicating how much more readily body heat would be transferred away to the surrounding environment. Compared to conventional fabrics like cotton, wool, nylon, and silk, this new material transfers heat anywhere from 5-9 times more effectively.

electrospinning conceptual model
Conceptual model of the electrospinning process - [American Chemical Society]
closeup fibers boron nitride
Close-up views of the fabric showing the fibers coated with boron nitride, and the pores in-between - [American Chemical Society]
thermal conductivity fabric boron nitride
Thermal conductivity through various fabrics compared to the new material (red star) - [American Chemical Society]