It sounds like one of those commercials you see on day-time television for a better stain-removing spray, but even Mr. Clean can't do this: Researchers at Monash University in Victoria, Australia, have created clothes — spun from natural fibers — that clean themselves.
The researchers discovered a way to coat clothes with titanium dioxide nanocrystals, which break down food and dirt in sunlight. Titanium dioxide is a component of sunscreens, toothpaste, and paint, and acts as a strong photocatalyst: In the presence of ultraviolet light and water vapor, it forms hydroxyl radicals, which oxidize (or decompose) organic matter. But the nanocrystals can't break down the garment and don't harm the skin, nor does the coating change the appearance or texture of the clothes.
It's not a new idea: Titanium dioxide powder has been applied to glass to make self-cleaning windows, and cotton clothes have also gotten the nanocrystal treatment. But coating natural fibers has proved more difficult, so the Australian researchers' success at producing wool, silk, and hemp clothes that come clean in the sunshine represents a big step forward. Their process is described online in the journal Chemistry of Materials.
And there are side benefits. Titanium dioxide also destroys bacteria in the presence of sunlight, which could make self-cleaning fabrics a good fit for hospitals. As the study's author, organic chemist Walid Daoud, put it: "Self-cleaning property will become a standard feature of future textiles ... particularly since pathogenic microorganisms can survive on textile surfaces for up to three months."
So how do the self-cleaning clothes stack up against the leading brand? Wool coated in titanium dioxide makes a red wine stain - a notoriously difficult blemish -- disappear after 20 hours in the sunshine, while coffee stains dissipate in only two hours. Hang on to your pocket protector, though: Blue-ink blotches hang around for 17 hours before melting away.