The large interest in nanostructures results from their numerous potential applications in various areas such as materials and biomedical sciences, electronics, optics, magnetism, energy storage, and electrochemistry. Ultrasmall building blocks have been found to exhibit a broad range of enhanced mechanical, optical, magnetic, and electronic properties compared to coarser-grained matter of the same chemical composition. In this paper various template techniques suitable for nanotechnology applications with emphasis on characterization of created arrays of tailored nanomaterials have been reviewed. These methods involve the fabrication of the desired material within the pores or channels of a nanoporous template. Track-etch membranes, porous alumina, and other nanoporous structures have been characterized as templates. They have been used to prepare nanometer-sized fibrils, rods, and tubules of conductive polymers, metals, semiconductors, carbons, and other solid matter. Electrochemical and electroless depositions, chemical polymerization, sol-gel deposition, and chemical vapour deposition have been presented as major template synthetic strategies. In particular, the template-based synthesis of carbon nanotubes has been demonstrated as this is the most promising class of new carbon-based materials for electronic and optic nanodevices as well as reinforcement nanocomposites.
PACS: 61.46.+w; 61.48.+c; 61.82.RxIn 1959 Richard Feynman, the future Nobel Laureate, suggested in his famous lecture, entitled "There's Plenty of Room at the Bottom", a variety of tests that might be achieved at very small scales. Three decades later Feynman's vision has become the greatest scientific frontier of the century. It opened a new field of "Nanostructures" having dimensions of about 10 to 1000 Å, a size that is small by engineering standards, common by biological standards, and large to chemists.The central thesis of nanotechnology is that almost any chemically stable structure that can be specified can actually be built. Nature has plenty of proof that nanotechnology works, from the liposomes in cells that manufacture proteins atom by atom, to the chloroplasts of plants that turn sunlight, carbon dioxide, and water into copies of themselves. Since biological machines exist, and work, and since biology follows the same laws of physics and chemistry applied by engineers, there's no question the nanostructural machines will work. Scientists have to figure out, however, how to build them.Of particular significance is the size dependence of many properties in nanomaterials, for example, an enhancement in the strength and hardness of solids; the possibility of modifications of their electrical properties by control of the arrangement within the constituent nanoclusters and of their assembly; the control of chemical reactivity by the attachment of functional side-groups; the control of optical properties by variation of the size and microstructure of the nanoclusters; the possibility of creating nanostructures of metastable phases with no...
