Nanomaterials and Nanoscience
are not simply another step in the miniaturization of materials or particles. They often require very different production approaches. There are several processes to create various sizes of nanomaterials, classified as ‘top-down’ and ‘bottom-up’. Although large numbers of nanomaterials are currently at the laboratory stage of manufacture, many of them already are being commercialized.
Below we outline some examples of nanomaterials and the range of nanoscience that is aimed at understanding their properties. As will be seen, the behavior of some nanomaterials is well understood, whereas others present greater challenges.
Nanoscale in One Dimension – Thin films, layers and surfaces
One-dimensional nanomaterials, such as thin films and engineered surfaces, have been developed and used for decades in fields such as electronic device manufacture, chemistry and engineering.
In the silicon integrated-circuit industry, for example, many devices rely on thin films for their operation, and control of film thicknesses approaching the atomic level is routine.
Monolayers (layers that are one atom or molecule deep) are also routinely made and used in chemistry. The most important example of this new class of materials is graphene.
The formation and properties of these layers are reasonably well understood from the atomic level upwards, even in quite complex layers (such as lubricants) and nanocoatings
. Advances are being made in the control of the composition and smoothness of surfaces, and the growth of films.
Engineered surfaces with tailored properties such as large surface area or specific reactivity are used routinely in a range of applications such as in fuel cells and catalysts. The large surface area provided by nanoparticles, together with their ability to self assemble on a support surface, could be of use in all of these applications.
Although they represent incremental developments, surfaces with enhanced properties should find applications throughout the chemicals and energy sectors.
The benefits could surpass the obvious economic and resource savings achieved by higher activity and greater selectivity in reactors and separation processes, to enabling small-scale distributed processing (making chemicals as close as possible to the point of use). There is already a move in the chemical industry towards this.
Another use could be the small-scale, on-site production of high value chemicals such as pharmaceuticals.
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