News Column

The nanotechnology in your clothes

February 13, 2014

Holly Cave, theguardian.com



The Consumer Products Inventory lists over 1,600 products that have been identified by the manufacturer as containing nanoparticles particles between one and 100 nanometres (between one and 100 billionths of a metre) across. Last month in this series on nanotech in household items, we looked at toothpaste. This month: clothing.

Several types of nanoparticles are added to the clothes we wear, including:

Microbe-killing silver

Silver nanoparticles are added to clothing for their powerful ability to kill bacteria and fungi, and to prevent the nasty odours they cause. Nanosilver particles release positively charged ions that stop bacterial cells functioning. The particles' tiny size means the garment stays soft and wearable.

Silica for waterproofing and stain resistance

Nanoparticles of silica incorporated into the weave of a fabric or sprayed onto its surface create a coating that repels water and stain-producing liquids. The angle and roughness of the silica coating creates enough surface tension to ensure that liquids form beads that roll off the fabric rather than soaking into it.

Sunblocking titanium dioxide and zinc oxide

Ever got sunburnt through your T-shirt? Nanoparticles of titanium dioxide or zinc oxide are incorporated into textiles to protect your garments and your skin from sun damage. Both particles scatter the ultraviolet light in sunlight, and do so more effectively as nanoparticles rather than as larger particles.

Antistatic particles

Some fabrics particularly synthetics such as polyester and nylon tend to gather static charge. Whisk a top over your head and your hair stands on end. But nanoparticles that conduct electricity, such as zinc oxide, titanium dioxide and antimony-doped tin oxide, can help disperse this charge.

At the moment, clothes featuring nanotechnology are largely made from standard fabrics upon which a nano-coating has been applied. But in the future we're likely to see more fabrics made from nanofibres, with nanoparticles and nanofilaments an integral part of the weave. A new era of "smart" fabrics, for example, could automatically respond to your body and the environment around you.

Safety

Natalie von Goetz from the Swiss university ETH ZÜrich has been studying whether the nanoparticles on fabric are dislodged during wear. "We tested whether nanoparticles are released into sweat under laboratory conditions, because if they are, they might be taken up by the skin," she explains. While clothes treated with titanium dioxide weren't found to release particles, nanosilver the most widely used nanoparticle in the world is shed from clothing in sweat.

Rickard Arvidsson from Chalmers University of Technology in Gothenburg, Sweden, thinks this could pose a problem. "While nanosilver and silver in general is not particularly toxic to humans, it could be very toxic to aquatic life," he explains. Arvidsson's research has shown that if nanosilver is extensively used in clothing, it could lead to high concentrations of silver in the sludge from waste water treatment plants.

Both he and von Goetz believe that research into their potential risks is lagging behind the commercialisation of nanomaterials.


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Source: Guardian Web


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