We know that the size and shape of materials influence their characteristics. Scientists found that materials having size about 1/1,000,000,000 metre show special characteristics. Then they started producing such kind of materials and studied the effect of size on properties. Thus a new branch of chemistry called 'Nanochemistry' was developed.
Nanochemistry is a branch of nanoscience, that deals with the chemical applications of nanomaterials in nanotechnology. It involves synthesis and manipulation of materials at atomic and molecular level and the study of their physical and chemical properties.
Nanotechnology is the application of science to manipulate matter to atomic or molecular scale and making use of them to develop specialized materials and devices for use in our day to day life. It deals with the materials which are smaller than 100 nanometres and hence it is so called.
The word, Nano has been derived from the Greek word 'Nanos' which is designated to represent billionth fraction of a unit. For instance, 1 Nanometre = 1/ 1,000,000,000 metre. Can you imagine how small is a nanoparticle?
The following examples may help to illustrate how small the nanoscale is.
· One nanometre (nm) is 10−9 or 0.000,000,001 metre.
· A nanometre and a metre can be understood as the same size-difference as between golf ball and the Earth.
· Our nails grow 1 nm each second.
· The virus most usually responsible for the common cold has a diameter of 30 nm.
· One nanometre is about one twenty-five-thousandth the diameter of a human hair.
· A cell membrane is around 9 nm across.
· The DNA double helix is 2 nm across.
· The diameter of one hydrogen atom is around 0.2 nm.
The method you have just used is called a Serial dilution. You can notice that in each tube, the food colouring is ten times more diluted than the previous tube. By the time they reach tube 9, the original food colouring would have been diluted to the level of one part of food colouring to a billion parts of water. At this stage, the intensity of colour and smell would be extremely low.
In such a way, when materials are broken down to nanoscale, they show some special surface properties which make them to be used for special kinds of applications. This type of manipulation of materials is done by nanotechnology.
How small is a nanoparticle? Visit the following link: https://www.youtube.com/ watch?v=38Vi8Dm0kdY
Nanomaterials have the structural features in between those of atoms and the bulk materials. The properties of materials with nanometre dimensions are significantly different from those of atoms and bulk materials. This is mainly because the nanometre size of the materials render them, larger surface area, high surface energy, spatial confinement and reduced imperfections, which do not exist in the corresponding bulk materials. Due to their small dimensions, nanomaterials have extremely large surface area to volume ratio, resulting in more 'surface dependent' material properties. As the surface characteristics of nanoparticles are the main criteria to be considered for applications, highly sophisticated instruments like Scanning Electron Microscope (SEM), Tunneling Electron Microscope (TEM) and Atomic Force Microscope (AFM) are used to analyse the surface properties of a nanoparticle with high resolution.
The range of commercial products available today is very broad, including stain-resistant and wrinkle-free textiles, cosmetics, sunscreens, electronics, paints and varnishes. Nanochemistry is applied in all these substance. Some of them are given below.
· The metallic nanoparticles can be used as very active catalysts.
· Chemical sensors from nanoparticles and nanowires enhance the sensitivity and sensor selectivity.
· Nano coatings and nanocomposites are found useful in making variety of products such as sports equipment, bicycles and automobiles etc.
· These are used as novel UV-blocking coatings on glass bottles which protect beverages from being damaged by sunlight.
· Nanotechnology is being applied in the production of synthetic skin and implant surgery.
· Nanomaterials that conduct electricity are being used in electronics as minute conductors to produce circuits for microchips.
· Nanomaterials have extensive applications in the preparation of cosmetics, deodorants and sun screen lotion and they are used to improve moisturizers without making them too oily.
· Nanoparticle substances are incorporated in fabrics to prevent the growth of bacteria.
· Biomedical devices like drug infusion pumps, microneedles and glucometer are made from nanomaterials.
· Nanochemistry is used in making space, defence and aeronautical devices
· Nanoparticles are unstable when they contact with oxygen.
· Their exothermic combustion with oxygen can easily cause explosion.
· Because nanoparticles are highly reactive, they inherently interact with impurities as well.
· Nanomaterials are usually considered biologically harmful and toxic.
· It is difficulty to synthesis, isolate and apply them.
· There are no hard-and-fast safe disposal policies for nanomaterials.