Size is important!

Particles made up of a few molecules

An object that is only a few nanometres in size might be built from a single molecule (large molecules, such as proteins, can be many nanometres in diameter), or perhaps just a small number of smaller molecules.

Soft materials

The rigidity we are used to in modern high-strength engineering materials comes from the way the atoms and molecules pack to form crystalline structures. This is sometimes improved by adding other atoms or molecules to the structure to prevent imperfections spreading throughout the material: this is what we mean by an alloy. However, some organic materials have shapes and structures that do not form crystals and are therefore very often floppy.

As a consequence, many of the materials we can build nano-structures from are flexible or 'soft'. This flexibility can be used to design molecules and materials that change shape in response to changes in their environment - so-called 'smart materials'.

Nano-bearings

It seems obvious that the almost perfectly spherical C60 molecule, Buckminsterfullerene, would be an ideal ball bearing on the nano-scale. Recent studies, however, have shown that if you lubricate two surfaces with 'buckyballs', the friction goes UP if the balls rotate while the surfaces are moved relative to each other.

In practice this means that buckyballs make better sledges than bearings - and this may be because they 'squish' as they rotate, and a lot of energy is dissipated by this deformation...

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