Self-cleaning fabrics now even cleaner

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A self-cleaning fabric that lasts longer, shows better antibacterial action and is more comfortable to wear than current materials

US scientists have made a self-cleaning fabric that lasts longer, shows better antibacterial action and is more comfortable to wear than current materials.

Fabrics treated with certain compounds such as N-halamines can produce oxidative species, which kill pathogens and degrade toxic chemicals. However, the compounds either degrade rapidly under sunlight or are only used to coat the fabric’s surface so are easily washed off.

Gang Sun and his team from the University of California, Davis, have incorporated 2-anthraquinone carboxylic acid (2-AQC) into cotton fabrics, which bonds strongly to the cellulose in cotton, making it harder to wash off. Under light exposure, 2-AQC produces reactive oxygen species, such as hydroxyl radicals and hydrogen peroxide, which provide the self-cleaning functionality.

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2-Anthraquinone carboxylic acid incorporated into cotton fabrics bonds strongly to the cellulose in the cotton (right image - 0.2M 2-AQC), making it harder to wash off than the compounds in current self-cleaning fabrics. The image on the left shows cotton fibres and the image in the middle shows cotton treated with 0.025M 2-AQC

The researchers applied this compound using a simple esterification reaction. The fabric was dipped into a mixture of 2-AQC and N,N-carbonyldiimidazole and was shaken for 24 hours. The simplicity of the procedure means that, during manufacture, it could be performed during the dyeing process, says Ning Liu, one of the researchers. The fabric showed better antibacterial action than previous materials. Although 2-AQC is more expensive than other compounds, Liu says cheaper equivalents could be used.

’The new fabric has potential applications in biological and chemical protective clothing for healthcare, food processing, and farm workers, as well as military personnel,’ Liu says.

Dave Worley, an expert in biocidal compounds at Auburn University, Alabama, US, is impressed by the advantages of using 2-AQC over earlier compounds. ’The best things going were N-halamines, but their primary limitation is the length of time that they can function in sunlight,’ he says. ’What we’ve got here is going to last longer, so that’s the big advantage.’

Sun and his team are now looking to find more photoactive anthraquinone compounds to investigate control of photoreactivity and improve durability on surfaces.

Yuandi Li