Nanomaterials

Nanomaterials describe, in principle, materials of which a single unit is sized (in at least one dimension) between 1 to 1000 nanometres (10−9 meter) but usually is 1 to 100 nm (the usual definition of nanoscale).Viral capsid'Lotus effect', hydrophobic effect with self-cleaning abilityClose-up of the underside of a gecko's foot as it walks on a glass wall (spatula: 200 × 10-15 nm)SEM micrograph of a butterfly wing scale (× 5000)Peacock feather (detail)Brazilian Crystal Opal. The play of color is caused by the interference and diffraction of light between silica spheres (150 - 300 nm in diameter).Blue hue of a species of tarantula (450 nm ± 20 nm) Nanomaterials describe, in principle, materials of which a single unit is sized (in at least one dimension) between 1 to 1000 nanometres (10−9 meter) but usually is 1 to 100 nm (the usual definition of nanoscale). Nanomaterials research takes a materials science-based approach to nanotechnology, leveraging advances in materials metrology and synthesis which have been developed in support of microfabrication research. Materials with structure at the nanoscale often have unique optical, electronic, or mechanical properties. Nanomaterials are slowly becoming commercialized and beginning to emerge as commodities. There are significant differences among agencies on the definition of a nanomaterial. In ISO/TS 80004, nanomaterial is defined as the 'material with any external dimension in the nanoscale or having internal structure or surface structure in the nanoscale', with nanoscale defined as the 'length range approximately from 1 nm to 100 nm'. This includes both nano-objects, which are discrete pieces of material, and nanostructured materials, which have internal or surface structure on the nanoscale; a nanomaterial may be a member of both these categories. On 18 October 2011, the European Commission adopted the following definition of a nanomaterial: 'A natural, incidental or manufactured material containing particles, in an unbound state or as an aggregate or as an agglomerate and for 50% or more of the particles in the number size distribution, one or more external dimensions is in the size range 1 nm – 100 nm. In specific cases and where warranted by concerns for the environment, health, safety or competitiveness the number size distribution threshold of 50% may be replaced by a threshold between 1% to 50%.' Engineered nanomaterials have been deliberately engineered and manufactured by humans to have certain required properties. Legacy nanomaterials are those that were in commercial production prior to the development of nanotechnology as incremental advancements over other colloidal or particulate materials. They include carbon black and titanium dioxide nanoparticles. Nanomaterials may be incidentally produced as a byproduct of mechanical or industrial processes. Sources of incidental nanoparticles include vehicle engine exhausts, welding fumes, combustion processes from domestic solid fuel heating and cooking. For instance, the class of nanomaterials called fullerenes are generated by burning gas, biomass, and candle. It can also be a byproduct of wear and corrosion products. Incidental atmospheric nanoparticles are often referred to as ultrafine particles, which are unintentionally produced during an intentional operation, and could contribute to air pollution.