What is Nanotechnology?
Nanotechnology is a field of research and innovation concerned with building 'things' - generally, materials and devices - on the scale of atoms and molecules. A nanometre is one-billionth of a metre: ten times the diameter of a hydrogen atom. The diameter of a human hair is, on average, 80,000 nanometres. At such scales, the ordinary rules of physics and chemistry no longer apply. For instance, materials' characteristics, such as their colour, strength, conductivity and reactivity, can differ substantially between the nanoscale and the macro. Carbon 'nanotubes' are 100 times stronger than steel but six times lighter.
WHAT ARE NANOPARTICLES?
A nanoparticle is a small particle that ranges between 1 to 100 nanometres in size. Undetectable by the human eye, nanoparticles can exhibit significantly different physical and chemical properties to their larger material counterparts.
The particle size of at least half of the particles in the number size distribution must measure 100 nm or below. Most nanoparticles are made up of only a few hundred atoms.
The table below shows the size of nanoparticles compared to other structures:
| Particle Type | Diameter Size Range |
|---|---|
| Atoms and small molecules | 0.1 nm |
| Nanoparticies | 1 to 100 nm |
| Fine particles (also called particulate matter PM2 s) | 100 to 2,500 nm |
| Coarse particles (PM,0, or dust) | 2500 to 10,000 nm |
| Thickness of paper | 100,000 nm |
The material properties change as their size approaches the atomic scale. This is due to the surface area to volume ratio increasing, resulting in the material’s surface atoms dominating the material performance. Owing to their very small size, nanoparticles have a very large surface area to volume ratio when compared to bulk material, such as powders, plate and sheet. This feature enables nanoparticles to possess unexpected optical, physical and chemical properties, as they are small enough to confine their electrons and produce quantum effects.
What is the difference between normal products and nanoparticles products?
Nanoparticles have a considerable size effect and high surface activity. The nanoparticles which are very smaller in size, their addition can fill the matrix's pores, reduce its porosity, increase its relative density, and improve its mechanical properties. The surface area to volume ratio for a material or substance made of nanoparticles has a significant effect on the properties of the material. Firstly, materials made up of nanoparticles have a relative larger surface area when compared to the same volume of material made up of bigger particles. As particle size decreases, a greater proportion of the particles are found at the surface of the material which is more reactive and also enhance the desired characteristics of the materials.
Nanoparticles often have unexpected visible properties because they are small enough to confine their electrons and produce quantum effects, due to its very high surface area to volume ratio which provides a tremendous driving force for diffusion, especially at elevated temperatures. Nanomaterials have attracted extensive attention due to its size, surface effect and quantum tunneling effect, as well as potential applications in traditional materials, medical devices, electronic devices, coatings and other industries. Nanomaterials have excellent mechanical properties due to the volume, surface and quantum effects of nanoparticles. As nanoparticles are added to a common material, these particles will refine the grain to a certain extent, forming an intragranular structure or an intergranular structure, thereby improving the grain boundary and promoting the mechanical properties of materials. For Example, adding 3 wt % nano-SiO2 to concrete can improve its compressive strength, bending strength, and splitting tensile strength. Nanomaterials have excellent mechanical properties and unique properties that are not found in macroscopic materials, they have broad application prospects in the future.
Types of Nanomaterials
Nanomaterials could be organized into two types: