Nanomaterials and their applications

Introduction to nanomaterials and their applications
1. INTRODUCTION
1.1. What is nanomaterial
Generally, nanoscience is the science of studying matter at extremely small sizes - nanometers (nm). One nanometer is equal to one billionth of a meter (m) or one millionth of a millimeter ( mm). Nanotechnology is the technology related to the design, analysis, manufacturing, and application of structures, equipment and systems by controlling the shape and size at the nanometer scale (from 1 - 100nm).
Nanoparticles actually exist for millions of years in the natural world. Since the 10th century, people have used gold nanoparticles to create glass, ceramics of different colors (red, blue or yellow depending on the size of the particle) ... That means humans have used, fabricated nanomaterials for a long time, only we don't know much about it.
1.2. Where did nano-technology originate?
In 1959, the concept of nanotechnology was mentioned by American physicist Richard Feynman when he mentioned the ability to fabricate matter at the microscopic scale from the collection of atoms and molecules. In the 1980s, thanks to the advent of a wide range of analytical equipment, including scanning probe microscopes (SEM or TEM) which are capable to observe the size of several atoms or molecules, humans could observe and better understand nano field.
1.3. Why nano-materials are interesting?
The interesting properties of nanomaterials come from their very small size, which can be compared to the critical dimensions of many physical and chemical properties of the material. Nanomaterials lie between the quantum properties of the atom and the mass properties of the materials. For bulk materials, the critical length of properties is very small compared to the size of the material, but for nanomaterials it is not true so the strange properties start from the cause.
1.4. Synthesis methods
Nanomaterials can be fabricated using four common methods, each with strengths and weaknesses, some of which can be applied to some materials depending on the material requirements, laboratory equipment conditions ...
a. Wet chemical methods
Wet chemical methods include hydrothermal, sol-gel, and co-precipitation methods. In this method, different ionic solutions are mixed together in an appropriate proportion. Under the effect of temperature, pressure, or pH conditions, nanomaterials are precipitated from the solution. After the filtration and drying processes, nanoscale materials are obtained.
The advantage of wet chemical methods is that the materials that can be manufactured are very diverse. They can be inorganic, organic, metal materials. While this method is inexpensive and can produce a large amount of material, it also has the disadvantage which are the assocication of water molecules into the obtained material, low yield, inhomogeneous products.
b. Mechanical method (Nano-Mechanical Method)
This approach includes methods of canopy, grinding, mechanical alloys. In this method, materials in powder form are ground to smaller size. Today, the most commonly used crushers are planetary or rotary crusher. The mechanical method has the advantage of being simple, inexpensive fabrication tools requirement and the capability of producing a large quantities of material. However, it has the disadvantage that particles are agglomerated, particle size distribution is inhomogeneous and susceptible to contamination from fabrication tools and it is often difficult to achieve small sized particles. This method is often used to create non-organic materials such as metals.
c. Thermal evaporation method
These include lithography, physical and chemical vacuum deposition. These methods are effectively applied in fabrication of thin films or surface coatings. One can also use it to make nanoparticles by scraping nanomaterials from the shield. However, this method is not very efficient to fabricate materials on a commercial scale.
d. Gas-phase method
These include pyrolysis, electro-explosion, laser ablation method, high temperature, plasma evaporation. The principle of these methods is to form nanomaterials from gas phase. Pyrolysis is a long-standing method used to create simple materials like carbon and silicon. Laser combustion can create a wide range of materials but is limited to the laboratory because of their low efficiency. One-way and alternating plasma methods can be used to create many different materials but are not suitable for creating organic materials because its temperature can reach 9000oC.
Nanomaterials are manufactured at the Department of Chemistry with the use of wet chemical methods including hydrothermal, sol-gel, and co-precipitation methods. According to this method, solutions containing different ions are mixed together in an appropriate proportion, under the action of temperature, pressure, pH conditions, etc.
This method is cheap and can fabricate a large amount of material.


2. NANO TECHNOLOGY APPLICATIONS Nanotechnology allows the manipulation and use of materials at the molecular level, increasing and creating special properties of materials, reducing the size of devices and systems to extremely small sizes. Nanotechnology helps replace traditional pollutant chemicals, materials and manufacturing processes with a new, lightweight, energy-efficient, environmental-impacting process. Nanotechnology is considered an industrial revolution, promoting development in all fields, especially biomedical, energy, environment, information technology, military ... and affecting the whole society.
In biomedicine: Nanoparticles are considered to be nano-robot that allow humans to intervene at the molecular or cellular scale. Currently, humans have created nanoparticles with biological properties that can be used to support disease diagnosis, drug transmission, and destruction of cancer cells.
Energy: improving the quality of solar batteries, increasing the efficiency and reserve of batteries and supercapacitors, creating superconductors as electrical wires for long-distance transportation ...
Electronics - mechanical engineering: manufacturing nano electronic components with extremely fast processing speed, manufacturing generations of nano computers, using nanomaterials to make extremely small information recording devices, computer or mobile screens, creating ultralight though super durable nanomaterials for the manufacturing of car, aircraft, spacecraft ...
Environment: creating nano membranes that filter out polluting molecules; nano catalyst for quick and complete waste water treatment ...