Nanotechnology and Nano Materials
- (University of Michigan at Ann Arbor)
- What is a Nanomaterial?
Nanomaterials are chemical substances or materials that are manufactured and used at a very small scale. Nanomaterials are developed to exhibit novel characteristics compared to the same material without nanoscale features, such as increased strength, chemical reactivity or conductivity.
ISO (2015) defines a nanomaterial as a material with any external dimension in the nanoscale (size range from approximately 1 – 100 nm) or having internal structure or surface structure in the nanoscale.
Nanomaterials that are naturally occurring (e.g., volcanic ash, soot from forest fires) or are generated as incidental (unintentional) by-products of combustion processes (e.g., welding, diesel engines) are usually physically and chemically heterogeneous and often termed ‘ultrafine particles’. Engineered nanomaterials, on the other hand, are intentionally produced and designed with physical-chemical properties for a specific purpose or function.
- Classifications of Nanomaterials
Nanomaterials can be roughly classified according to their total number of nanometer sizes:
- If all three dimensions of a material are nanoscale, it is called a 0D (zero-dimensional) material, often referred to as a nanoparticle.
- If two dimensions of a material are nanoscale, and the other dimension is much larger (like a string shrinking to a tiny size), then it's a one-dimensional material or "nanotube/nanowire".
- If only one dimension was nanoscale, then it would be a 2D material—similar to a large but very thin sheet (like a sheet of paper).
- Finally, a material is not a nanomaterial if it does not have any dimensions small enough to be considered nanoscale. Instead, it should be called "bulk" material, the class we deal with in our daily lives.
- What are the Uses of Nanomaterials?
Due to the ability to generate the materials in a particular way to play a specific role, the use of nanomaterials spans across various industries, from healthcare and cosmetics to environmental preservation and air purification.
The healthcare field, for example, utilises nanomaterials in a variety of ways, with one major use being drug delivery. One example of this process is whereby nanoparticles are being developed to assist the transportation of chemotherapy drugs directly to cancerous growths, as well as to deliver drugs to areas of arteries that are damaged in order to fight cardiovascular disease. Carbon nanotubes are also being developed in order to be used in processes such as the addition of antibodies to the nanotubes to create bacteria sensors.
In aerospace, carbon nanotubes can be used in the morphing of aircraft wings. The nanotubes are used in a composite form to bend in response to the application of an electric voltage.
Elsewhere, environmental preservation processes make use of nanomaterials too - in this case, nanowires. Applications are being developed to use the nanowires - zinc oxide nanowires- in flexible solar cells as well as to play a role in the treatment of polluted water.
- [Structure of Atom - Tutorialspoint]
- Advantages of Nanomaterials
The properties of nanomaterials, particularly their size, offer various different advantages compared to the bulk-form of the materials, and their versatility in terms of the ability to tailor them for specific requirements accentuates their usefulness. An additional advantage is their high porosity, which again increases demand for their use in a multitude of industries.
In the energy sector, the use of nanomaterials is advantageous in that they can make the existing methods of generating energy - such as solar panels - more efficient and cost-effective, as well as opening up new ways in which to both harness and store energy.
Nanomaterials are also set to introduce a number of advantages in the electronics and computing industry. Their use will permit an increase in the accuracy of the construction of electronic circuits on an atomic level, assisting in the development of numerous electronic products.
The very large surface-to-volume ratio of nanomaterials is especially useful in their use in the medical field, which permits the bonding of cells and active ingredients. This results in the obvious advantage of an increase in the likelihood of successfully combatting various diseases.
- Disadvantages of Nanomaterials
Alongside their benefits, there are also a number of disadvantages associated with nanomaterial use. Due to the relative novelty of the widespread use of nanomaterials, there is not a large amount of information on the health and safety aspects of exposure to the materials.
Currently, one of the main disadvantages associated with nanomaterials is considered to be inhalation exposure. This concern arises from animal studies, the results of which suggested that nanomaterials such as carbon nanotubes and nanofibers may cause detrimental pulmonary effects, such as pulmonary fibrosis. Further possible health risks are ingestion exposure and dust explosion hazards.
Additionally, there are still knowledge gaps regarding nanomaterials, meaning the manufacturing process can often be complex and difficult. The overall process is also expensive, requiring optimum results - especially regarding their use in consumer goods - in order to avoid financial losses.
Risk-assessments concerning any potential environmental effects indicate that nanomaterials used in cosmetic items such as sunscreen, which are applied to the skin, run the risk of ending up in aquatic ecosystems after they are washed off. Nanomaterials that have been engineered may also end up in water bodies such as lakes and rivers, before accumulating to create particles of a larger size. This may put freshwater species - such as snails- at risk by possibly inducing a decline in life processes such as growth and reproduction. The same issues caused by the materials in such freshwater ecosystems are likely to pertain to marine ecosystems as well. Accumulation of nanomaterials in other aspects of the environment, such as soils - through sewage sludge - is an additional concern. Although the concentrations of these engineered nanomaterials is expected to be quite small, repeated release may cause the concentrations to increase over time, exacerbating the related negative effects.
[More to come ...]
