Ellen Phiddian
Cosmos science journalist
High-tech textiles might be a smart way to reduce the toll on humans in heating cities. Some, based on lotus leaves, might even repel rain.
A new paper published in Science Bulletin highlights several fabrics developed by different teams of researchers, which can passively cool bodies and buildings.
These fabrics, argue the authors, could keep people cool in urban heat islands, reducing the need for air conditioning and other energy intensive measures.
They work by radiation cooling: allowing heat to escape via infrared radiation, while reflecting visible sunlight.
“Unlike conventional fabrics that retain heat, these textiles are made of three layers that are engineered to optimise cooling,” says Yangzhe Hou, an engineer at Zhengzhou University in China and visiting academic at the University of South Australia.
One particular fabric, designed by another team of Chinese researchers, included polymers and wool.
“This cooling fabric is a polymethylpentene fabric prepared via electrospinning. Afterward, a silver nanowire dispersion was sprayed on its surface, and once dried, holes were punched to improve air permeability,” Hou tells Cosmos.
Then the team sewed a wool layer on the underside, resulting in a triple-layered, cooling fabric.
When used as a horizontal surface cover, the underside of the fabric was 6.2°C cooler than surrounds. When hanging horizontally, as it might on a garment, the fabric was 2.3°C than traditional textiles.
While such a fabric would be more expensive than a poly-cotton T-shirt, Hou says that electrospinning and the other processing methods are fairly easy to scale industrially.
“This fabric can be made into a milky white garment, with a material that closely resembles everyday clothing. The wool fabric on the underside adds comfort against the skin,” says Hou.
“While the colour can be altered through dyeing or other techniques, it’s worth noting that light-coloured tones reflect sunlight more effectively, enhancing the cooling effect, whereas dark tones like black would absorb more sunlight and reduce cooling performance—similar to the reason we wear light-coloured clothes in summer.”
The team at Zhengzhou University, led by Professor Xianhu Liu, has been investigating various ways to make fabrics like this more durable.
“Several approaches can be taken,” says Hou.
“Promoting polymer crystallisation can enhance its resistance to UV degradation, weathering, and moisture.”
This involves letting the long polymer molecules on a fabric solidify in a way that makes them form regular, repeating patterns at the molecular scale.
“Designing micro- and nano-structures, similar to the surface of a lotus leaf, can increase hydrophobicity, helping to repel rain and maintain cooling performance even in wet conditions.”
Water-repelling, or hydrophobic, clothing, is less vulnerable to water damage.
“Incorporating UV-absorbent nanofillers into the polymer matrix can further improve UV resistance and overall durability,” adds Hou.
“All these factors are key considerations in future durability studies.”
