Nanotechnology will improve existing processes and give existing materials new qualities. These prospects are based on new materials properties which are based on their size beeing at the transition between atoms and bulk materials. They can therefore possibly combine properties of both atoms and bulk materials This is based on three vectors, which obviously are not independent of each other.
Nanomaterials have advantages due to their small size.
They can better interact with biological molecules because nanomaterials have a similar size. Therefore the interaction of nanomaterials with biological systems is in the focus of current investigations. Researchers see progress in the realm of drug delivery as well as targeting, diagnostics and cancer research.
A stable suspension, a mixture of a solid in a liquid component, can be more easily achieved by using nanoparticles. Normal sand particles from a beach will sediment in water, whereas corresponding nanoparticles would form a suspension stable for months.
Nanomaterials have advantages due to their high specific surface.
The surface of a similar weight of a nanomaterial is much larger when compared to a bulk material. This effect has clear advantages in applications where the surface is limited.
In heterogeneous catalysis the production rate of a chemical is limited by the available surface It is also known that surface atoms have a very different behavior than bulk atoms located at the inside of a material. This explains why gold nanoparticles are interesting for catalysis, while gold in bulk form is known as a inert noble material,. Unsaturated gold nanoparticles are able to partial oxidize hydrocarbons (Haruta M Catalysis today 36 1997). Why can we use gold nanoparticles for reactions ins catalysis?
Unsaturated surface atoms are responsible for this effect. Comparing a 1 cm sphere and a 10 nm sphere, we can calculate that for the nanoparticle spheres 10% of all atoms are located on the surface whereas the amount of surface atoms is negligible for the 1 cm sphere. The smaller a sphere, the higher the percentage of particles located on the surface. Therefore, this behavior is determined by unsaturated surface atoms which lead to measurable quantum mechanical effects. These effects per se are nothing new with nanoparticles they become more apparent. As a result, nanotechnology has found application in catalysis since the end of the last century.
For reactive materials such as gypsum or portland cement the corresponding nanoparticles have a higher specific surface which leads to a faster hardening reaction. This effect is also used used to design biomaterials with new and improved properties.
Nanomaterials have advantages due to quantum mechanical effects.
These effects are based on the fact that the size of a nanomaterial (e.g. a semiconductor) is in the same range as the “de Broglie” wavelength of an electron (1-10 nm). At the beginning of the last century, researchers have established models to define the probability of the location of an electron. When this area contains a nanoparticle quantum mechanical effects can occur. This explains why such quantum mechanical effects normally occur only for nanomaterials smaller than 20 nm in diameter.
Image by courtesy of Prof. Weller (http://www.chemie.uni-hamburg.de/pc/weller/)
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