Researchers at Donghua University in China have developed a new type of fabric they claim can keep the wearer much cooler. The material is made from several different polymers in a relatively simple way, and can efficiently transfer heat and wick away sweat, while remaining water repellent from the outside.
The material is composed of three main components: polyurethane, which forms the basic structure, fluorinated polyurethane, which is water repelling, and boron nitride nanosheets, which conduct heat. The three are combined and run through an electrospinning instrument to form membranes with nanoscale fibers.
The resulting membranes take the form of polymer nanofibers coated in boron nitride, giving the material the properties of all three ingredients. The boron nitride helps to transfer heat from the body out to the open air; the large pores between fibers lets air circulate through to the skin, as well as helping moisture evaporate and escape; and despite the large pores, the material remains water repellent on the outside, thanks to the fluorinated polyurethane.
The team ran several tests to demonstrate the material’s abilities. In one, they stretched a sample out between two chambers – one filled with air below, and one filled with water above. The material was able to prevent the water from soaking through and dripping into the lower chamber, while at the same time allowing the air from below to pass through and bubble up through the water.
In another test, the team placed a sample of the material onto a small heater, which was simulating human body heat. Then they measured how much heat it had transferred through over time, and compared that to a sample of another material that didn’t contain boron nitride. The new material was more efficient at heat transfer – after 40 seconds its surface temperature was about 2.2 °F (1.2 °C) warmer than the other.
It might not be the smartest cooling material out there, but the team says it's relatively easy to produce. Besides use in clothing that helps cool the wearer, the team says that the new material could also be useful for cooling down electronics, as well as improving devices that collect solar energy or desalinate seawater.
The research was published in the journal ACS Applied Materials & Interfaces. The team describes the work in the video below.
Source: American Chemical Society
