Saturday, September 14, 2013

What is Nantechnology?

Nanotechnology makes use of materials whose structures have characteristic features on the nanoscale (i.e., on the scale of 10-9 meter [a nanometer, nm]). Obviously, this size is a very small one compared to objects we have around ourselves, but it is not particularly small on an atomic scale. Indeed, characteristic distances between atoms in a solid are of the order of 10-10 meter (a tenth of a nanometer, also called an Ångström), so a piece of material whose side is one nm may contain hundreds or up to a thousand atoms. This means that, normally, a nanomaterial shows some resemblance to a normal solid comprising the same atoms, but it is typically modified to achieve some superior property such as higher strength, different electromagnetic properties, permeability to a fluid, or some other quality. A higher strength may mean that less material is needed to accomplish a given task; different electromagnetic properties may mean that we can harness the sun’s rays more efficiently in a solar energy conversion device or that we can build better electrical generators, and achieving a desired permeability may lead to improved filtering technology to remove undesired substances from water or air. Of course, these examples can be multiplied almost ad infinitum.
Thus, nanotechnology enables us to achieve material properties that were previously impossible, impractical, or too expensive for use on a scale large enough to have a global impact on energy use and supply. Almost certainly nanomaterials will continue to surprise us for years to come with unexpected characteristics and new applications. This also makes them attractive for scientists looking for stimulating research avenues.
In the past, more complex materials — apart from new chemical compounds, including new polymers — were prepared by alloying, impurity doping, and making composites involving microscale or larger size additives. These processes were the main sources of the new materials that then led to emerging technologies and major advances in human capabilities and lifestyles. While a few examples of nanomaterials for decorative applications can be found in antiquity, a scientific approach for their development started only some 30 to 40 years ago. The science of nano-materials, what we call nanoscience) has accelerated rapidly over the last two decades, thereby opening up new vistas and many opportunities for materials design. This research field is so vast and diverse that at present it is largely unexplored. Such diversity can be counter-productive, though, and means that good scientific understanding and a strategic approach to materials development are essential, because empirical possibilities at the nanoscale are almost endless. To draw an analogy, it is as though we had suddenly developed the practical ability to travel the universe and needed to decide where to head first, knowing little of what would be out there.
This article thus provides strategies for the use of nanoscience to give unprecedented abilities for tuning material properties to human needs, to keep economies humming along without intolerable degradation of the environment. The dominant energy technologies that will emerge from those strategies will ultimately have to be manufactured and implemented on huge areas, such as 20 or 100 million square meters per annum, to achieve the dual goals of largely improved energy efficiency at affordable prices and significant energy from renewables. These are commodity scales, such as those applying in current flat glass and metal sheet output. Commodity-scale volumes usually only arise if the product is cheap enough. It is fascinating that we are thus exploiting our ability to engineer at the tiniest scale of approximately 108 square meters to achieve advanced materials and technologies that can be affordably produced on scales of 108 square meters each year. In fact, commodity volumes of systems containing nanoscale features are already in existence, including in the latest computer chips and in multilayer coatings on windows for saving energy.
Why this emphasis on large area? It will be needed for two reasons apart from economics: first, because various renewable energy sources are highly dispersed, and second, because in order to save energy it will be necessary to use novel materials and coatings for windows, walls, and roofs of most of our buildings and appliances, and for our various means of transport.