Nanotechnology Lect.2

Fundamental ?Nano-Effects‘
? The macroscopic physical properties of a substance (melting point, boiling point, conductivity, etc.) are determined by studying a pure sample in quantities big enough to be measured under normal laboratory conditions. One mole of any material contains 6.022 x 1023 molecules; one mole of water, for instance, weights 18 g. Therefore, when the boiling point of one mole of water is determined, in reality the value which is obtained represents an average value based on the behavior of billions and billions of molecules of water; we assume that the result should be true for any size of group of water molecules. This is not correct for many materials: as the size of the material is reduced, and the nanoscale level is reached, it is possible that the same material will display totally different properties (different melting point, conductivity, etc.). This is because matter at the nanoscale no longer follows Newtonian physics but rather quantum mechanics.
A different kind of small
Materials that belong to the ?nanoscale‘ are made of at least clusters of atoms and molecules, not just single atoms: for example, 3.5 atoms of gold or eight hydrogen atoms lined up in a row are one nanometre long. A glucose molecule is about 1 nm in size.
Nanomaterials represent a ?different kind of small‘ compared to other ?small‘ objects that a student might be familiar with. Nanomaterials are not as small as electrons or single atoms, and are bigger than other ?very small objects‘, such as a cell or bacterium, that a student can probably think of. Nanostructures are at the confluence of the smallest human-made objects (e.g. latest-generation transistors) and the largest molecules of living things (e.g. DNA, proteins). Nanomaterials are intermediate in size between isolated atoms and molecules, and bulk materials. At this scale, matter shows exceptional properties.
Nanomaterials offer two exciting possibilities:
1. Nanomaterials can be used to improve current materials or create new ones that have exceptional properties.
2. As nanomaterials have dimensions in the range of the largest molecules found in the natural world, it is possible to integrate them and interact actively with them in a device.