Nanotechnology is a multidisciplinary field. It includes such fields as material science, applied physics, interface and colloid science, supramolecular chemistry, device physics, chemical engineering, biological engineering, mechanical engineering and electrical engineering. Through the principle of molecular recognition, molecules assemble themselves chemically. Examples of nanotechnology include the designing of computer chips and the manufacture of polymers.
Most of the commercial application of nanotechnology has taken the advantage of colloidal nanoparticles that are in bulk form such as cosmetics, sustan lotion, protective coatings and drug delivery as well as stain resistant type of clothing (Fritz and Patrick 2008 ). Basic concepts of nanotechnology One nanometer is equivalent to one billionth of a meter. This same equivalent is like comparing the size of a marble to the size of the earth. In the modern synthetic chemistry it is possible to prepare small molecules to nearly any structure.This has been applied in chemistry to produce such molecules as commercial polymers and pharmaceuticals.
By the use of a bottom up approach, the same techniques are being sought in supramolecular chemistry and or molecular self assembly to arrange molecules to useful conformation (Clarence 2007). From the concept of molecular recognition it is important to have a specific arrangement so as to favor the non-covalent intermolecular forces. It is from this that Watson-Crick rules of basic pairing were developed, or the case of specificity in enzyme action or even the specific conformation of proteins (Lynn 2005).It is on this regard that two or even more components can be developed to be mutually attractive as well as complementary so as to have a better useful whole product. There are basically two main approaches used in nanotechnology. The ‘bottom up’ and the ‘top down’ approach.
For the ‘bottom up approach’, devises and materials are built basically from molecular components which do assemble themselves chemically through the principle of molecular recognition. For the ‘top down approach’ the nano objects are usually constructed from the larger entities that do not involve atomic level control (Fritz and Patrick 2008 ).These kinds of interests in nanotechnology comes from the Interface and Colloid Science interests that is now coupled to such analytical tools as atomic force microscope (AFM), and also the scanning tunneling microscope (STM) (Clarence 2007). When these instruments are combined with such processes as molecular beam epitaxy and the electron beam lithography, the instruments do give an opportunity for the deliberate nanostructure manipulation hence leading to the observation of some novel phenomenon (Lynn 2005).As the particle size decreases, so does various phenomenon such as quantum mechanical effects and the statistical mechanical effects do become clear. In this regard, electronic properties of various solids are altered as the particle size is reduced.
This phenomenon only becomes evident if the nanometer size is reached and hence it does not just occur by the virtual of macro to micro dimension changes.Physical properties such as electrical, mechanical and optical properties of the system are also known to change when the size is altered and a good example is the increase in surface area to the volume ration that does eventually alter the thermal, mechanical and the catalytic properties of the material. It is currently appreciated that matter exists at nanoscale and thus when matter is reduced to nanoscale, it can show different properties compared to the macro scale properties hence giving an opportunity for some unique applications (Lynn 2005).An example is the conversion of opaque substances to transparent one (copper), solids in to liquids at room temperature (gold), stable materials can be turned into combustible ones (aluminium), and even the insulators can become conductors (silicon). Materials such as gold which are chemically inert within the normal scales can serve as chemical catalyst at nanoscales (Fritz and Patrick 2008 ).
Construction of simple to complex structure It is in the modern synthetic chemistry where it is now possible to convert small molecules into almost any desirable structure.Molecular nanotechnology also called molecular manufacturing is an engineering nanosysten that does operate at the molecular scale. It is associated with the molecular assembler concept which is a device that has the potential to device atom by atom to produce a desired structure by employing mechanosynthesis principles (Clarence 2007). Materials qualify as nonmaterial if they have unique properties that do emerge from the nanoscale dimension.
From the interface and colloid science there have been various materials that have come up such as carbon nanotubes, nanorods, nanoparticles and fullerenes that can be useful in nanotechnology.The bottom –up approach This is a n approach that does seek to arrange smaller material components in to the more complex assemblies. An example is the DNA nanotechnology the specificity derived from the Watson_crick base pairing to come up with nucleic acids and even some well defined DNA structures. The construction of well defined structures such as bis-peptide is also another from of approach. In general, the molecular self assembly does seek to utilize the molecular recognition and supramolecular chemistry concepts to cause automatic arrangement of single molecules into some desired useful conformation (Lynn 2005).Top-down approach In this kind of an approach, technology has been descending from the common solid state silicon methods of fabricating microprocessors into the creation of features that are smaller than 100nm.
An example in this category is the giant magnet resistant based hard drives and the atomic layer deposition (ALD) technique (Clarence 2007). Some of the current speculative approaches to nanotechnology include molecular nanotechnology, nanorobotics and programmable matter that is based on artificial matter. Molecular nanotechnology involves the manipulation of single molecules within a finely controlled deterministic manner.At the moment it is beyond current capabilities.
The nanorobotics center upon a self sufficient machine of certain functionality operating at nanoscale. This is hoped to be applied in medicine though there are several drawbacks on it and may thus not be easy to do so (Fritz and Patrick 2008 ).. Technique The first size measurement and observations of nano-particles were made in the early 20th century. There are certain technique that were developed in Interface and Colloid Science for the characterization of nanomaterials.These are currently widely used for the first generation passive nanomaterials.
Some of the applied methods include light scattering, ultrasound attenuation spectroscopy and the ultrasound that are applied to test the concentration of microemulsion and nano-dispersions. Electrophoretic light scattering, electroacoustics and microelecrophoresis are some of the methods used to characterize zeta potential and surface charge of some nano particles in solution. Colloid vibration current is used in the characterization of concentrated systems (Clarence 2007).Techniques such as deep ultraviolet lithography, focused ion beam machining, electron beam lithography, nanoimprint lithography, molecular vapor deposition and atomic layer deposition as well as some of the molecular self-assembly technique are some of the techniques used ion the fabrication of nanowires. It is through the designing of different tips for these kinds of microscope that different structures are curved out as well as self assembly given an opportunity.
An example is the use of feature oriented scanning positioning approach where atoms are moved around one surface with a scanning probe microscopy technique.This kind of an approach is both time consuming and expensive for mass production though it is suitable for laboratory experimentations (Fritz and Patrick 2008 ). In contrast to this is the bottom up technique where large structure are built atom by atom or molecule by molecule. Applied techniques here include self-assembly, chemical synthesis and positional assembly (Lynn 2005).
Some of the new technique such as Dual Polarization Interferometry are being used to quantitatively measure the molecular interaction at the nano-scale.It is from a variation of bottom up approach, molecular beam epitaxy (MBE), that devices and samples are made in the field of spintronics. Nanocarbons There is an active research in this field where conditions for the optimization of reaction conditions for oxidative dehydrogenation of ethylene benzene are being sought. Towards this end there are several searches that include 1.
Search for nanocarbons that do have improved stylene conversion selectivities, conversion rates and prolonged life times for the large scale production. 2. Oxygen partial pressure role in the ODH of ethylbenzene.Carbon tube-in-tube (CTIT) nanostructures can be built from a narrower tube inside an outer tube.
It does exhibit several intramolecular channels that is beneficial for the improvement of its properties. Though CTIT are difficult to assemble, graphic nanopartices can be disintegrated into smaller fragments by the use of HNO3 based type of oxidation at the defective sites. In this process that was previously used to cut, purify and open nanotubes is used to fragment the edges with hydroxyl and carboxyl groups (Fritz and Patrick 2008 )..Conclusion It is so far claimed that there are over 609 nanotech products available with even new ones coming up every week. Most of the current applications are limited to the first generation passive nanomaterials that includes some food products and cosmetic and titanium dioxide in sunscreen (Lynn 2005).
Other products include surface coatings, zinc oxide in cosmetics and sunscreen, and carbon allotropes that are used in the gecko tape. There is much more research needed in the field of nano materials production especially in future applications that would require the actual arrangement or manipulation of the nanoscale components.
