Classification of nanomaterials12
Nanomaterials can be categorized as different methods of classification including origin, dimensions and their structural configuration
A. According to their origin nanomaterials are classified as:
1. Natural nanomaterials: Nanomaterials which are belonging to resource of nature are defined as natural nanometer. As per examples virus, protein molecules including antibody originated from nature are some natural nano structured materials. In addition following are few examples, mineral such as clays,natural colloids, such as milk and blood (liquid colloids), fog (aerosol type), gelatine (gel type),mineralised natural materials, such as shells, corals and bones,Insect wings and opals,Spider silk,Lotus leaf and similar(Nasturtium,). Gecko feet,volcanic ash, ocean spray etc
2. Artificial nanomaterial: Artificial nanoparticles are those which are prepared deliberately through a well-defined mechanical and fabrication process. The examples of such materials are carbon nanotubes, semiconductor nanoparticles like quantum dots etc.
B.On the other hand according to the dimensions nanomaterials also can be divided into zero dimensional, one dimensional, two dimensional and three dimensional nano materials. (Fig. 3)
Fig. 3 Different dimensional Nanomaterials (a) 0-D spheres and clusters, (b) 1-D nanofibers, wires,and rods, (c) 2-D films, networks, (d) 3-D nanomaterials.
1. Zero dimensional(0-D):These nanomaterials have Nano-dimensions in all the three directions. Metallic nanoparticles including gold and silver nanoparticles and semiconductor such as quantam dots are the perfect example of this kind of nanoparticles. Most of these nanoparticles are spherical in size and the diameter of these particles will be in the1-50 nm range. Cubes and polygons shapes are also found for this kind of nanomaterials.
2. One dimensional(1-D):In these nanostructures, one dimension of the nanostructure will be outside the nanometer range. These include nanowires, nanorods, and nanotubes. These materials are long (several micrometer in length), but with diameter of only a few nanometer. Nanowire and nanotubes of metals, oxides and other materials are few examples of this kind of materials
3. Two dimensional(2-D):In this type of nanomaterials, two dimensions are outside the nanometer range. These include different kind of Nano films such as coatings and thin-film-multilayers, nano sheets or nano-walls. The area of the nano films can be large (several square micrometer),but the thickness is always in nano scale range
4. Three Dimensional(3-D):All dimensions of these are outside the nano meter range. These include bulk materials composed of the individual blocks which are in the nanometer scale (1-100 nm)
C. On the basis of structural configuration nanomaterials can be classified into four types:
Carbon Based Nano materials: The nature of this kind of nanomaterials is hollow spheres, ellipsoids, or tubes. Spherical and ellipsoidal configured carbon nanomaterials are defined as fullerenes, while cylindrical ones are described as nanotubes.
Metal Based Materials: The main component of these particles is metal. These nanomaterials include nanogold, nanosilver and metal oxides, such as titanium dioxide and closely packed semiconductor like quantum dots.
Dendrimers: Dendrimers are highly branched macromolecules with the dimensions nanometer-scale. The surface of a dendrimer posses numerous chain which can be modified to perform specific chemical functions. PAMAM dendrimer is the best illustration of this kind of materials.
Composites: Nanocomposite can be described as a multiphase solid material where at least one of the phases has one, two or three dimensions in nanoscale. The most common examples of these materials are colloids, gels and copolymers.
12. Introduction to nanomaterials. Alagarasi. http://www.nccr.iitm.ac.in/2011.pdf.
1.According to origin nanomaterials can be classified into natural and artificial nanomaterials.
2.On the basis of dimension nanomaterials can be classified into zero dimensional, one dimensional, two dimensional and three dimensional forms.
3. Nanomaterial can be classified according to different structural configuration of the material like carbon based nanomaterials, metal based nanomaterials etc