Introduction to Nanoscience and Nanomaterials
Keywords:Nanotechnology, small structures, subnanometer, nanomaterial, micro fabrication
Nanotechnology is a technology that deals with small structures or small-sized materials with the dimension that spans from subnanometer to several hundred nanometers, where a nanometer (nm) is one billionth of a meter. According to the EU rules "nanomaterial means a natural, incidental or manufactured material containing particles in a bounded state or as an aggregate or as an agglomerate where, for 50% or more of the particles in the number size distribution, one or more external dimensions are in the size range of 1-nm-100 nm". Apart the different opinions regarding nanotechnology, it is identified in EU as a key-enabling technology driving innovation. At "this dimension level”, in fact,” the physical, chemical, and biological properties of materials differ in fundamental and valuable ways from the properties of individual atoms and molecules of bulk matter". The industrial strategies to be adapted for producing at nano level are not yet clear, but the processing techniques may have the top-down or bottom-up approaches. Attrition or milling is a typical top-down method in making nanoparticles, whereas the colloidal dispersion is a good example of bottom-up approach in the synthesis of nanoparticles. Among others, the biggest problem with top-down approach is the imperfection of the surface structure, such as the crystallographic damage in lithography. In any way, bottom-up is the way all the plant and biological structures are making, combining a simple nanostructure to form higher level building block hierarchical structures. They form higher level building blocks that further self assemble to give the next level of structure and so on.