Cotton has many appealing characteristics as a clothing fabric, offering great breathability, insulation and of course comfort. A group of scientists in China has come up with a novel coating for everyday cotton that gives it an even broader set of useful traits, enabling it to repel oil and water with ease, and most impressively, float even when bearing loads many times its own weight.
While a popular fabric for a number of reasons, one thing cotton can't offer is an ability to repel water and oils, which means it simply soaks them up and is therefore quite susceptible to stains. Researchers have been working on so-called superamphiphobic coatings that can bestow regular cotton with the water- and oil-repelling capabilities, and with some success. But the methods are difficult, time-consuming and involve many steps, meaning they aren't presently viable for large-scale manufacturing.
Among the material scientists tinkering away in this area is a team from China's Wuhan University of Technology, who have developed a comparatively simple "one-pot" coating technique that involves just a single step. The scientists mix dopamine hydrochloride and a pair of molecules together with a piece of cotton fabric for 24 hours. This causes a chemical reaction that sees the ingredients bond together to form a uniform, dark brown coating on the fabric.
Through subsequent testing, the team showed that this new coating made the regular cotton impermeable to many common liquids, and not just at the surface. The inner cotton fibers were found to be liquid-proof too. Fine sand, meanwhile, could be easily washed away with water. Only when subjecting the material to strong acid did its water resistance become compromised, while repeated washing was found to lessen its oil resistance.
Interestingly, the technique was also found to create nanoscale pockets of air at the point where the coating attached to the fabric. This enabled the cotton to float in water even when bearing up to 35 times its own weight, and 27 times its own weight when floating in oil.
According to the scientists, these attributes open up some interesting possibilities around functional fabrics that could find use in buoyant swimming suits that are possibly just as comfortable a regular ones, and also repel water. They could also find use in more comfortable lifejackets or protective clothing.
The research was published in the journal ACS Applied Materials & Interfaces, while the video below offers a look at the some of the scientists' experiments.
Source: American Chemical Society