Nanomaterials

A 7 Point Introduction to Nanomaterials Used In The World Today

The terms nanotechnology and nanomaterials are popping up more often in the news, in research papers and even on the web. Despite that, there is still a relative lack of awareness regarding nanomaterials.

1. Definition of Nanomaterials

Before understanding the concept of nanomaterials, there is need to understand what the general concept of nanotechnology is all about.

The term ‘nanotechnology’ emerged in 1974. At the time, it was defined as consisting of the processing of separation, consolidation, and deformation of materials by one atom or by one molecule.

According to the United States National Nanotechnology Initiative, nanotechnology seeks to understand and control matter measuring between 1 and 100 nanometers and subsequently produce materials and components that have unique characteristics which are then used in different applications.

It is worth noting that a nanometer is equivalent to a billionth of a meter.

Nanomaterials are among the main products of nanotechnology. Nanomaterials are also defined as those materials which have structured components that have at least one external dimension measuring less than 100 nanometers. Nanomaterials may exist in the form of particles, rods, tubes or fibers.

2. Two Different Construction Techniques

Scientists can use two different techniques to construct/produce nanomaterials. The first of these is called the Top Down technique. This involves producing Nanoscale structures from larger materials. For example, one may etch the surface of a silicon microchip to create circuits.

The second technique used to produce nanomaterials is the Bottom Up technique where nanomaterials are constructed atom by atom or one molecule by another.

One way is through self-assembly where atoms/molecules structurally arrange themselves as a result of their natural properties. A good example of this is the chemical synthesis of larger molecules.

There is a second way of constructing using the bottom-up technique i.e. the positional assembly method. Here, researchers use specific tools to move individual atoms/molecules.

However, this method is not so popular because it is labor intensive and is therefore not suitable for large scale use.

Construction Techniques - Nanomaterials

3. Dimensions Of Different Nanomaterials

Different nanomaterials have different dimensions in the Nanoscale. Below are some of these dimensions;

  • Layers such as graphene, thin films, and surface coatings have one nanoscale dimension and two extended dimensions.
  • Nanowires and nanotubes are nanoscales in 2 dimensions
  • Particles such as precipitates, colloids and even nanocrystalline materials have three nanoscale dimensions.

4. Differentiating Between Nanomaterials And Bulk Materials

There are two main factors behind the distinct difference between nanomaterials and other materials. One is the increased relative surface area while the second is about the quantum effects.

Changes in these two factors can result in changes in properties such as strength, reactivity, and even electrical characteristics.

Nanoparticles, for example, have relatively larger surface areas than those of much larger particles. According to experts, a decrease in particle size gets accompanied by an increased number of atoms on the surface rather than on the inside.

A particle measuring 30 nanometers may have just 5% of its atoms on the surface while a 10-nanometer particle may have as many as 20% on the surface. The increased size makes nanomaterials more reactive than their identical self in bulk/larger form.

On the other hand, as the particles undergo size reduction to the nanoscale, the dominance of quantum effects on the properties of the materials. This, in turn, affects the unique properties of the nanomaterials e.g. optical, mechanical, electrical and even magnetic properties.

For example, if grains in metal were to undergo reduction to nanoscale size, the interface area within the metal would increase subsequently enhancing the strength of the metal.

5. Some Properties Of Nanomaterials

i. Physical Properties

It is a fact that the smaller nanomaterials are, the stronger the quantum effect. Zinc, for example, does not have superior UV blocking capabilities in bulk form. However, in nanoparticle form, zinc has superior UV blocking properties.

When it comes to gold, the bulk form melts at extremely high temperatures of up to 1064  °C. However, a 2.5-nanometer gold nanoparticle melts at -300  °C.

ii. Optical Properties

Nanomaterials may also have some rather unexpected optical properties. Gold nanoparticles, for example, appear to change colors from deep red to black when placed in a solution.

iii. Magnetic Properties

While this is a useful property, it is not always a wanted property. According to research, ferroelectric materials that are smaller than 10 nanometers have the ability to change the direction of their magnetization using room temperature thermal energy. This makes them unsuitable for the storage of memory.

6. Application Of Nanomaterials

Nanomaterials are currently in use in various industries for a range of applications right from health to industrial applications. Some potential uses of nanomaterials include;

  • Applications that could allow scientists to add antibodies to nanotubes to form bacteria sensors. There is also the possibility of adding boron or gold to nanotubes to trap oil spills.
  • Some possible applications of graphene sheets include as electrodes in ultracapacitors which will have storage similar to batteries but a shorter recharge time of minutes.
  • Scientists are researching the use of nanofibers to stimulate cartilage production in damaged joints. Others are exploring the use of nanofibers in clothing to power cell phones and other devices.
  • The use of nanoparticles for therapeutic delivery to cells, prevention of autoimmune diseases and even for cleaning up oil spills is also under research.

 

Health and Environment Effects - Nanomaterials

7. Effects of Nanomaterials

There are two kinds of effects of nanomaterials: health and environment effects.

i. Health Effects

There is evidence to suggest that nanoparticles may affect biological and health systems negatively. For example, airborne nanoparticles can influence organs such as the lungs and possibly even affect the heart and blood circulation.

Nanoparticles may also trigger the formation of fibrous protein tangles just like some brain diseases. Research has also shown that nanoparticles when used in gene therapy, may damage the genes through inflammation.

ii. Environmental Effects

Increased use of nanomaterials is expected to cause an increased risk of environmental exposure. However, there is still little knowledge on how nanomaterials behave when exposed to air, water or soil.

Experiments have demonstrated possible negative effects on the behavior, reproduction and even the development of fish and invertebrates.

More research is still required to ascertain these findings and also ascertain the effect of nanomaterials on the environment.

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