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Nanomaterials, nanotechnology, nanocomposites are today's buzzwords in the scientific & business world. This review paper attempts to understand the subtle nuances and explore their significance and usefulness. The basics of nanomaterials, nanotechnology & their relevance to polymers, chemicals & minerals, which are used as additives & modifiers for developing high performance & value-added nanocomposites have been covered.
Nanomaterials
Nanomaterials (nanocrystalline materials) are materials possessing grain sizes of the order of a billionth of a meter. They manifest extremely fascinating & useful properties, which can be exploited for a variety of structural & nonstructural applications. All materials are composed of grains, which in turn, comprise many atoms. These grains are usually invisible to the naked eye, depending on their size. Conventional materials have grains varying in size anywhere from 100's of microns (um) to millimeters (mm). A micron (um) is a micrometer or a millionth (10 ^ -6) of a meter. An average human hair is about 100 um in diameter. A nanometer (nm) is even smaller than a micrometer and is a billionth (10^-9) of a meter.
A nanocrystalline material has grains of the order of 1 � 100 nm. The average size of an atom is of the order of 1 to 2 Angstroms (A^o) in radius. 1 nanometer comprises 10Angstroms; hence in one nm there may be 3 to 5 atoms, depending on their radii. Nanocrystalline materials are exceptionally strong, hard, and ductile at high temperatures, wear resistant, corrosion resistant, erosion resistant & chemically very active. Nanocrystalline materials or nanomaterials, are also much more formable than their conventional, commercially available counterparts.
here are five widely known methods to produce nanomaterials & they are as follows:
• Sol-gel synthesis
• Inert gas condensation
• Mechanical alloying or high �energy ball milling
• Plasma synthesis
• Electro deposition
Classification of Nanomaterials for Commercial Purposes Including Nanoparticles, Fullerenes, Dendrimers, Nanowires, Nanotubes, Nanolayers and Nanopores
All conventional materials like metals, semiconductors, glass, ceramic or polymers can in principle be obtained with a nanoscale dimension. The spectrum of nanomaterials ranges from inorganic or organic, crystalline or amorphous particles, which can be found as single particles, aggregates, powders or dispersed in a matrix, over colloids, suspensions and emulsions, nanolayers and films, up to the class of fullerenes and their derivates. Also supramolecular structures such as dendrimers, micelles or liposomes belong to the field of nanomaterials. Generally there are different approaches for a classification of nanomaterials, some of which are summarised in table 1. The main classes of nanoscale structures are summarised below table 1.
Dimension |
3 dimensions < 100nm |
Particles, quantum dots, hollow spheres, etc. |
2 dimensions < 100nm |
Tubes, fibres, wires, platelets, etc. |
1 dimension < 100nm |
Films, coatings, multilayer, etc. |
Phase composition |
Single-phase solids |
Crystalline, amorphous particles and layers, etc. |
Multi-phase solids |
Matrix composites, coated particles, etc. |
Multi-phase systems |
Colloids, aerogels, Ferro fluids, etc. |
Manufacturing process |
Gas phase reaction |
Flame synthesis, condensation, CVD, etc. |
Liquid phase reaction |
Sol-gel, precipitation, hydrothermal processing,etc. |
Mechanical procedures |
Ball milling, plastic deformation, etc. |
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