It can be frustrating when you leave the house in a suit and find that you have made the wrong dress. Put on a jacket that keeps you warm and during the day it starts to get warm. A nightmare: and I must say that I am a champion in this sport, but I am certainly not the only one.
The jackets made with a new fabric experimental reversible, however, can solve the problem by cooling or warming the wearer.
Take the clothes the right way
Developed by scientists from China's Zhejiang University and Westlake University, the reversible, multi-layered "Janus fabric" is made from a base of polymer fibers ePTFE (expanded polytetrafluoroethylene). Other substances have been bonded to those fibers, giving the fabric a side that warms the user and one that helps keep them cool.
How the reversible "two-temperature" fabric works
Let's start with the obvious: the fabric changes condition depending on the direction. When worn with the heating side facing out, the zinc and copper nanoparticles on that side absorb solar energy and reduce the amount of body heat that escapes. If the user turns the garment inside out, the porous PMMA (polymethyl methacrylate) polymer coating on the now outward-facing cooling side reflects sunlight and helps dissipate body heat.
The laboratory tests: warmer than black cotton, cooler than white cotton
In tests performed under natural sunlight, the heating side increased the temperature of the simulated skin underneath compared to the black cotton. When the fabric was turned over, the cooling side reduced the skin temperature compared to the cotton White. The cooling side had no effect during the night test: the heating side turned out to be warmer than the black cotton.
According to scientists, the reversible fabric is easy and inexpensive to produce. Janus offers breathability similar to that of cotton. An added bonus, by connecting a thermoelectric generator to the material, the researchers were able to produce even a (small) amount of electricity by exploiting the temperature difference between the inner surface of the tissue and the skin.
Hopefully, when developed further, this reversible fabric feature can be used to power wearable electronic devices.
