Attack of the nanopants

Howard Lovy reports a televised encounter between some nanopants and a sticky fluid, in which the nanopants came off the worse.

Nanopants (or nanotrousers to any local readers) are garments whose fabric has been treated with the textile treatments of the Nano-tex corporation to improve their resistance to staining. Nanopants have become a bit of a touchstone to where people stand in the controversial matter of deciding what nanotechnology actually is. To followers of the Drexlerian view of nanotechnology (MNT) they are a symbol of how the word nanotechnology has been debased to cover all kinds of mundane, incremental applications of technology, far removed from the original grand vision. The pro-MNT blogger Glenn Harlan Reynolds simply calls them fake. But Nano-tex, to the nanobusiness community, is a splendid example of how nanotechnology can transform even traditional industries. Where does the truth lie?

I looked up the Nano-tex patents, in an attempt to establish whether the nano in these pants is real or simply marketing hype. There are 18 of them, and it isn’t obvious which technology is used in which product, but the general idea is clear enough. A typical product will be a copolymer – two or more chemically different polymer chains that are chemically attached to each other. One type of polymer will be hydrophilic, and this will tend to stick to a cotton or wool fibre, and the other part is hydrophobic. These hydrophobic bits of the chain will arrange themselves away from the textile surface, presenting a water and stain resistant surface to the outside world.

Two questions – is this novel, and is it nanotechnology? From the point of view of a scientist (rather than a patent lawyer) it clearly isn’t that new. It’s the same basic idea as 3M’s Scotchgard‚Ñ¢, invented in 1956 – this technology is also based on a copolymer, in this case an acrylic backbone on which water-repellant fluorocarbon side-chains are grafted. This works in just the same way as Nano-tex’s molecules – the acrylic backbone sticks to the fibre surface, leaving the water-repellant side-chains to coat the surface with a non-stick layer. But nonetheless, I do think it is nanotechnology, albeit of rather a rudimentary kind. A molecule has been defined with a specific architecture which codes the information it needs to form a specific nanoscale structure (in this case, sticky hydrophilic bits next to the textile surface, non-stick hydrophobic bits on the outside). It exploits the principle of self-assembly, which, as I explain in chapter 5 of my book Soft Machines, is the principle by which the sophisticated nano-machines of cell biology are constructed, and which we will learn to use in ever more sophisticated ways to make synthetic nano-devices.

But if nanopants really are nanotechnology, does that not imply that 3M have been doing nanotechnology since at least 1956, without using the label? Well, in this sense, yes. So the final lesson should probably be that the use of nano as a label for incremental products like this does owe a lot to marketing, but that doesn’t mean they don’t involve sophisticated technology. It’s just that other products without the nano label may in fact be just as nano-enabled.