Nanoscience changes things

Nanoscience is an emerging area of science that involves the study of materials on an ultra-small scale and the novel properties that these materials demonstrate. But how small is nanoscale small?

A nanometre (nm) is 10^-9, which is one-thousandth of a micrometre, or one-billionth of a metre. This is the scale at which we measure atoms and the molecules they make.

Exciting things begin to happen when you go ultra-small. Essentially, this is the scale at which quantum effects start to dominate the properties of materials.

What does this mean? Well, the physical and chemical properties of matter change. Consider a lump of gold, yellow in colour. If you were to break that lump into nanosized chunks, the gold would change colour depending on the size of the chunks. In the 10 to 100 nanometre range it can appear reddish (as well as orange, purple or green depending on the size or shape of the particle). Gold is also a catalyst in this size range but chemically inert at the larger micro or macro scale.

Indeed, by breaking down a ‘bulk’ material into nanosized particles you can often change many of its properties. By controlling the manner in which nanometre-scale molecular structures are formed, it is possible to control the fundamental properties of the materials these molecules build: properties such as colour, electrical conductivity, melting temperature, hardness, crack resistance and strength.

This is quite amazing when you consider that we are not changing the chemical composition or the crystal structure of the substance. We’re not adding a red pigment to the gold, just working with it in much smaller pieces. The physical and chemical properties change because we’re opening up and exposing more of the material’s surface area.

When particle sizes are reduced to the nanoscale, the ratio of surface area to volume increases dramatically. Since many important chemical reactions―including those involving catalysts―occur at surfaces, it is not too surprising that very small particles are staggeringly reactive. This is one of the reasons that chemists are very excited about nanoscience―if they can make more surface area, they can get more catalytic action, with the potential to speed up almost all physical and manufacturing processes, while improving the resource and energy efficiency of those processes and products.

There’s no doubt about it, small is the next big thing.