Nanometers are units of length, and 1 nanometer is 10-9 meters. For macroscopic materials, nanometers are a very small unit. Because the grain size is much finer than that of conventional materials, the number of atoms on the grain boundary is much larger. The number of atoms inside the crystal grains gives the nanomaterials many special properties. Compared with conventional materials, in addition to excellent mechanical properties, nanomaterials also exhibit better physicochemical properties, including optoelectronic, electromagnetic and thermal properties.
It is generally believed that nanomaterials should include two basic conditions: one is that the feature size of the material is between 1 and 100 nm, and the other is that the material at this time has some special physicochemical characteristics that distinguish the conventional size materials. From the research status so far, there are three concepts about nanotechnology.
The first is the molecular nanometer concept proposed by American scientists in 1986. According to this concept, a machine for combining molecules can be put to practical use, so that all kinds of molecules can be arbitrarily combined and any kind of molecular structure can be manufactured.
The second concept positions nanotechnology as the limit of microfabrication technology. That is, the technology of artificially forming nano-sized structures through nano-precision "processing". This nano-scale processing technology also makes semiconductor miniaturization reach its limit. Even if the existing technology continues to develop, it will theoretically reach the limit. This is because if the line width of the circuit is made small, the insulating film constituting the circuit will be extremely thin, which will destroy the insulating effect. In addition, there are issues such as fever and shaking. To solve these problems, researchers are researching new nanotechnology.
The third concept is made from the perspective of biology. Originally, organisms have nanoscale structures within cells and biofilms.
Nano-packaging technology can be divided into four categories. Crystals with dimensions at least in one direction in the order of a few nanometers are called three-dimensional (3) nanomaterials; those with a layered structure are called two-dimensional (2)
Nanomaterials; those with fibrous structures called one-dimensional (1) nanomaterials; those with atomic groups and atomic beam structures called zero-dimensional
(0) Nanomaterials. After more than ten years of development, nanomaterials have grown in size. Nowadays, there are many types of nanomaterials, which can be divided into metal materials, nano-ceramic materials, nano-semiconductor materials, nano-polymeric materials, nano-composites, etc. according to their materials. They are more or less applied in the packaging field.
With the increase in the demand for special functions of packaging in the 21st century, such as explosion-proof packaging, anti-electromagnetic packaging, camouflage packaging, high-resistance packaging, shadow packaging, and anti-radar packaging have emerged, and the development of nano packaging technology has been promoted. The nano-composite packaging material made of nano-materials has become a kind of high-tech material we need. It not only greatly improves the performance of raw materials and gives it new functions, but also broadens the application scope and bright prospects of raw materials. It also saved Greece's lack of resources.
At present nanomaterials have not only been put into production, but also have a large-scale application.
1 Nanoelectronics, optoelectronics and magnetism
The macroscopic tunneling effect of nanoparticles establishes the limit of miniaturization of microelectronic devices. Within a decade will reach the limit. The thinking of solving nano electronic circuit can be divided into two kinds at present, one kind is to use the quantum entanglement state in the photon to make the integrated circuit in the double photon beam technology, it is possible to limit the limit of the device to 25nm. The other is the development of new materials to replace silicon, using protein diodes, carbon nanotubes as the lead and molecular wires. The formation of new concept devices, single atom manipulation is an important way.
2 Nanomedicine and Biology
From proteins, DNA, RNA to viruses, all are in the scale of 1-100nm, so nanostructures are also the basic things in life phenomena. Organelles and other structural units in cells are "nanomachines" that perform certain functions. Cells are like nanometer workshops. Photosynthesis in plants is a typical example of a "nanofactory." Nanoparticles are often smaller than cells and red blood cells in organisms, which provides new opportunities for medical research.
Biochips under development include cell chips, protein chips (biomolecule chips), and gene chips (ie, DNA chips), which have the advantages of integration, parallel, and rapid detection, and have become cutting-edge technologies in nanobioengineering. Will be directly applied to clinical diagnosis, drug development and human genetic diagnosis. After being implanted in the human body, people can enjoy medical care anytime and anywhere, and they can find disease precursors in dynamic detection, making early diagnosis and prevention possible.
Nano wards do not harm normal tissues or remove thrombus, fat deposits from cardiovascular and cerebrovascular diseases, and even use them to engulf viruses to kill cancer cells. The other category is nanomaterials developed using the activity of biomolecules. They can be used in other organisms, but they can be used in other nanotechnology or biomaterials. They can also be divided into two categories. One is nano that is suitable for organisms. Materials, such as various types of nanosensors, are used for early diagnosis, monitoring and treatment of diseases. Various types of nanomechanical systems can quickly identify the location of the ward and inject drugs into the microfabrication.
3 Application in National Defense Science and Technology
Nanotechnology will have a revolutionary impact on the defense military field. For example: nanoelectronic devices will be used for virtual training systems and real-time contact on the battlefield; nano-detection systems for chemical, biological, and nuclear weapons; new nanomaterials can improve the ability to combat and prevent conventional weapons; and small-scale manufacturing from nano-micro mechanical systems. The robot can complete special reconnaissance and strike missions; the nanosatellite can launch thousands of satellites with a small launch vehicle, compose a satellite network according to different orbits, monitor every corner of the globe, and make the battlefield more transparent. The application of nanomaterials in stealth technology is particularly eye-catching.
In radar stealth technology, the preparation of ultra-high frequency electromagnetic wave absorbing materials is the key. Nanomaterials are being developed as a new generation of stealth materials.
4 Nano-ceramic reinforcement and toughening
Advanced ceramic materials play an irreplaceable role in other harsh environments such as high temperature and strong corrosion. However, brittleness is a weakness that ceramic materials cannot overcome. Nano-ceramics have similar metal-like superplasticity as the focus of attention in nanomaterials research. At present, the preparation of nano-ceramic powders is relatively mature, new technologies and new methods are emerging, and the production scale is already available. The preparation methods of nano-ceramic powders mainly include gas phase method, liquid phase method, and high-energy ball milling method. The gas phase method includes an inert gas condensation method, a plasma method, a gas pyrolysis method, an electron beam evaporation method, and the like. The liquid-phase method includes a chemical precipitation method, an alkoxide solution method, a sol-gel method, a hydrothermal method, and the like.
5 Applications in Catalysis Catalysts play an important role in many fields of chemical engineering. They can control reaction time, increase reaction efficiency and reaction speed. Nanoparticles are used as catalysts in semiconductor photocatalysts, especially in the preparation of organic materials.
6. Applications in Coatings Nanomaterials, due to their unique surface and structure, have excellent properties that are difficult to obtain with common materials and exhibit a strong vitality. Surface coating technology is also a hot spot in the world today. Nanomaterials provide a good opportunity for surface coatings, making it possible to functionalize materials. With the help of the traditional coating technology and the addition of nano-materials, nano-composite coating can be obtained, achieving a leap in function and making the traditional coating function modified. The nano-coating has a good application prospect and will bring a new technological revolution to the coating technology, and will also promote the research, development and application of composite materials.
7. Application in other fine chemicals
Fine chemical industry is a huge industrial field with a large number of products and a wide range of uses, and it affects all aspects of human life. The superiority of nanomaterials will undoubtedly bring a gospel to fine chemicals and show its unique strength. Nanomaterials can play an important role in the fields of fine chemicals such as rubber, plastics, and coatings.
Nanoscience is an emerging science that integrates basic and applied sciences, including nanoelectronics, nanomaterials, and nanobiology. The 21st century will be the era of nanotechnology. The application of nanomaterials involves various fields, and has broad application prospects in the fields of mechanics, electronics, optics, magnetism, chemistry and biology. The birth of nano-science and technology will have a profound impact on human society, and it may fundamentally solve many problems faced by mankind, especially major issues such as energy, human health and environmental protection. Nanomaterials will become a shining star in the field of materials science. It will play a decisive role in new materials, energy, and information. With the continuous development of its preparation and modification technologies, nanomaterials will be increasingly widely used in many fields such as fine chemical and pharmaceutical production.
Source: Plastic Packaging Committee
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