Nanotechnology - path to the future

Nanotechnology is a discipline which has been booming in many areas useful for humans such as medicine, engineering, computer and IT, materials, energy generation and consumer goods.

What is nanotechnology?

In simple terms, nanotechnology can be defined as a field of research and development involving building structures in nanometre scale (i.e. 1 - 100 nm). Nano is a Greek word for 'dwarf'. This implies that nanotechnology deals with very small things.

In scientific language, 'Nano' is used to denote 10-9. Hence a nanometre is one billionth of a metre (1/1,000,000,000).

To understand how small a nano particle - which has a diameter of 1-2 nm - is, look at this illustration (Pic 1). If this nano particle is big as a football, then the football is big as the Earth.

Carbon nano tubes and 'carbon bucky balls' are two important nano scale structures used in nanotechnology.

* Carbon bucky balls

C60 or carbon bucky ball is a nano scale spherical (round) molecule made of 60 carbon atoms arranged in a perfect symmetrical structure.

(See pic 2)

The diameter of a single C60 molecule is around 1-2 nm. These were first discovered in 1985 by three American scientists - Robert Curl, Harold Kroto and Richard Smalley.

They received the Nobel Prize for Chemistry in 1996 as this was a very important and useful discovery. Research is currently carried out using C60 molecules in research laboratories around the world, especially on producing fuel cells.

* Carbon nano tubes

The Carbon Nano Tube (CNT) is a tube-like structure generally made of carbon atoms assembled in hexagons. This was discovered by Sumio Lijima, a Japanese scientist, in 1991. The diameter of a single nano tube is around 2-4 nm and can be extremely long. When we compare this with human hair, it is 80,000 times smaller in diameter.

Nano tubes have extra ordinary physical properties. They are many times stronger than steel wires, lighter than aluminium, possess high heat conductivity and have different electrical properties.

Today, more and more CNT applications are moving from the research labs into commercial products. Now CNT is used for making high strength and lightweight tennis rackets and bicycles, producing smaller electronic devices and for various other applications in health care, aerospace and defence.

Currently, thousands of metric tons of nano tubes are produced annually, all over the world.

Nanotechnology is used to manipulate (manage) atoms, molecules and nano-size particles in a precise and well-controlled manner to build new materials with novel properties.

Current applications

Some of the key current and potential short-term applications of nano materials are given below. Most current applications represent evolutionary developments of existing technologies: for example, the reduction in size of electronic devices.

* Sunscreens and cosmetics

Nano-sized titanium dioxide and zinc oxide are currently used in some sunscreens, as they absorb and reflect ultraviolet (UV) rays and yet are transparent to visible light and so are more appealing to the consumer.

Nano-sized iron oxide is present in some lipsticks as a pigment, but it is understood that it is not used by the European cosmetics sector. However, the use of nano particles in cosmetics has raised a number of concerns about consumer safety.

* Clays

Clays containing naturally occurring nano particles are widely used as construction materials and are undergoing continuous improvements. Clay particle-based composites containing plastics and nano-sized flakes of clay are also becoming popular in applications such as manufacturing of car bumpers.

* Coatings and surfaces

Coatings with thickness controlled at the nano or atomic scale have been in routine production.

Recently developed applications include the self-cleaning window, which is coated in highly activated titanium dioxide, engineered to be highly hydrophobic (water repellent) and antibacterial, and coatings based on nano particulate oxides that destroy chemical agents. Wear and scratch-resistant hard coatings are significantly improved by nano scale intermediate layers (or multilayers).

Textiles

A range of enhanced textiles, such as breathable, waterproof and stain-resistant fabrics are also being developed with the help of nanotechnology. The dust and stain may not retain in the fabric as the pore sizes of these nano materials are smaller than the dust and stain particles.

Tougher and harder cutting tools

Cutting tools made of nano crystalline materials, such as tungsten carbide, tantalum carbide and titanium carbide, are more wear and erosion-resistant, and last longer than their conventional (customary) large-grained counterparts. They are finding applications in the drills used to bore holes in circuit boards. These cutting tools are tougher and harder than the conventional ones.

Paints

Incorporating nano particles in paints could improve their performance, for example, by making them lighter and giving them different properties. Thinner paint coatings ('light weighting'), used for example on aircraft, would reduce their weight and could be beneficial to the environment.

Nano paints are brighter and durable than conventional paints. Other novel, and more long-term, application of nano paint is producing paints which can change colour in response to change in temperature or chemical environment.

Fuel cells

One of the suggested solutions for the future fuel crisis is generating electric energy from fuel cells, especially for vehicles. Hydrogen is used as the immediate fuel in fuel cells, which can be generated from hydrocarbons by catalytic (induced) reforming.

The potential use of nano-engineered membranes to intensify catalytic processes could enable higher-efficiency, small-scale fuel cells.

One of the major practical concerns with regard to fuel cells is storing hydrogen in a portable manner. Research is being conducted to use nano materials such as fullerenes, as a hydrogen storage media.

Nano technology provides solutions to many problems currently faced by the people. As an outcome, it is widely becoming popular throughout the globe. We are certain to see many more applications of nanotechnology in the near future.

Reference: http://www.nanowerk.com, http://www.nanoforum.org/

Chintaka Nadun Ratnaweera, Scientific Officer, National Scientific Foundation.