Incremental nanotechnology — rebranding science

We can change the properties of many existing materials by taking control of their nano-scale structure. One elegant way of doing this is to use the tendency of certain molecules to self-assemble into coherent architectures. Soap molecules are expert at self-assembly, and can capture water in structures such as films and bubbles.

In fact most molecules self-assemble, but when the forces driving this are very strong, we end up with hard, crystalline masses! This tendency to self-assemble is actually a problem if you want to disperse ultra-strong carbon buckytubes in a resin to form a useful engineering composite, for example. Here the buckytubes have a tendency to stick together rather than to the resin, so it is proving harder than expected to make 'the toughest materials ever'...

Superhydrophobic coatings are an example where structure at the nano-scale imparts new and useful properties to a material. If we increase the surface area of a material then any water drop resting on this surface has to greatly increase its surface area in order to wet it. This results in a big increase in the surface energy of the water droplet. When the surface architecture gets down to nano-scale the water droplet tends to adopt a spherical or near spherical shape, and runs off the surface very quickly - taking any dirt with it!

Liposomes are an example of nano-structures that self-assemble from phospholipids. These form the membranes and much of the structural material of a living cell. They are not new to science, but perhaps their relationship to the radical claim that nanotechnology can make you immortal makes it attractive for cosmetics companies to market formulations containing liposomes as nanotechnology!

Which company has the largest portfolio of nanotechnology patents?

Many of the claims to nanotechnology might be labelled as rebranding existing products or technologies to make them a bit sexier. This doesn't mean to say that some properties are not genuinely dependent upon their being formulated from nano-scale particles. One such example is sun cream:

The active ingredient of sun cream is titanium dioxide, the same pigment used in white paint! The difference between emulsion paint and sun cream is in the particle size of the pigment. In paint the TiO₂ particles are about 0.3µm in size. At this size they scatter light, and appear white. When the size of the particles is dropped below this, however, they are no longer able to scatter visible light, but can still absorb UV. Commonly the particle size of TiO₂ for sun cream is between 10 and 20nm, and while any particle size would do, we wouldn't want to wear whitewash on the beach!

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