The two cooperation projects of "Functionalization of nano composite polyurethane synthetic leather materials" and "Application of nano materials in vacuum insulation panels" have made great progress. The polyurethane synthetic leather with anion release function and a release amount of more than 2000 conforms to the strategic upgrading direction of ecological and environmental protection synthetic leather, and a pilot scale study is to be carried out recently.
The successful R&D and further industrialization of this product will radiate and drive the upgrading of products of more than 300 peer enterprises. The thermal conductivity of the nanocomposite thermal insulation core prepared by the Alliance can be controlled as low as 4.4mW/mK. The product has been pilot produced in the enterprise, and a large-scale production line is under construction.
The Alliance will focus on the research and development of flame retardant high-efficiency vacuum insulation board and its application, research, development and industrialization in the field of building exterior wall insulation. The development of this technology will further promote the improvement of China's building energy conservation and environmental protection technology, and drive Anhui nano material industry into a high-speed development period.
In terms of size, the size of fine particles that usually produce significant changes in physical and chemical properties is less than 0.1 μ m (note 1 m=1000 mm, 1 mm=1000 μ m, 1 μ m=1000 nm, 1 nm=10 angstrom), that is, less than 100 nm. Therefore, particles with a particle size of 1-100 nm are called ultrafine materials, which are also nano materials.
Nanometer metal materials were successfully developed in the mid-1980s. Later, nano semiconductor films, nano ceramics, nano ceramic materials and nano biomedical materials came out one after another.
Nanometer structured materials are referred to as nanomaterials, which means that the size of their structural units ranges from 1 nm to 100 nm. Because its size is close to the coherent length of the electron, its properties are greatly changed due to the self-organization caused by strong coherence. Moreover, its scale is close to the wavelength of light, and it has the special effect of large surface, so its characteristics, such as melting point, magnetism, optics, heat conduction, conductivity, etc., are often different from the properties of the material in the overall state.
Nanoparticle materials, also known as ultrafine particle materials, are composed of nano particles. Nanoparticles, also called ultrafine particles, generally refer to particles with a size of 1~100nm, which are located in the transition zone between atomic clusters and macro objects. From the general viewpoint of micro and macro, such a system is neither a typical micro system nor a typical macro system, but a typical mesoscopic system, which has surface effect, small size effect and macro quantum tunneling effect. When macro objects are subdivided into ultrafine particles (nanometer scale), they will show many strange characteristics, that is, their optical, thermal, electrical, magnetic, mechanical and chemical properties will be significantly different from those of large solids.
The broad scope of nanotechnology can include nano material technology, nano processing technology, nano measurement technology, nano application technology, etc. Among them, nano material technology focuses on the production of nano functional materials (ultrafine powder, coating, nano modified materials, etc.), and performance testing technology (chemical composition, microstructure, surface morphology, physical, chemical, electrical, magnetic, thermal and optical properties, etc.). Nanomachining technology includes precision machining technology (energy beam machining, etc.) and scanning probe technology.
Nanomaterials have certain uniqueness. When the size of a substance is small to a certain extent, quantum mechanics must be used to replace traditional mechanics to describe its behavior. When the size of a powder particle is reduced from 10 microns to 10 nanometers, although its particle size changes to 1000 times, it will be 10 times to the ninth power when converted into volume, so there will be obvious differences between their behaviors.
The reason why nanoparticle is different from bulk material is that its surface area is relatively increased, that is, the surface of ultrafine particle is full of ladder structure, which represents unstable atoms with high surface energy. This kind of atoms can easily adsorb and bond with foreign atoms, and provide large surface active atoms due to particle size reduction.
As far as the melting point is concerned, because each particle in the nano powder has fewer constituent atoms, and the surface atoms are in an unstable state, which makes the vibration amplitude of the surface lattice larger, the nano powder has higher surface energy, resulting in the unique thermal properties of ultrafine particles, that is, the melting point drops. At the same time, the nano powder will be easier to sinter at a lower temperature than the traditional powder, thus becoming a good sintering promoting material.
Generally, common magnetic materials belong to the aggregation of multiple magnetic regions. When the particle size is too small to distinguish its magnetic region, it forms a magnetic material with a single magnetic region. Therefore, when magnetic materials are made into ultrafine particles or films, they will become excellent magnetic materials.
The particle size of nanoparticles (10 nm~100 nm) is smaller than the length of light wave, so they will have complex interactions with incident light. Under proper evaporative deposition conditions, the metal can obtain light absorbing black metal ultrafine particles, called metal black, which is in sharp contrast to the high reflectivity glossy surface formed by metal in vacuum coating. Nanometer materials can be used in infrared sensor materials because of their high light absorption. [1]
In 1861, with the establishment of colloidal chemistry, scientists began to study the particle system with a diameter of 1~100nm.
The really conscious research on nano particles can be traced back to the "smoke sinking test" carried out in Japan for military needs in the 1930s, but limited by the test level and conditions at that time, although the first batch of ultra fine lead powder in the world was made by vacuum evaporation, its light absorption performance is very unstable.
In the 1960s, people began to study discrete nanoparticles. In 1963, Uyeda made metal nanoparticles by gas evaporation and condensation, and studied them by electron microscope and electron diffraction. In 1984, Gleiter of Saarland University in Germany and Siegal of Argonne Laboratory in the United States successfully prepared nano fine powders of pure materials. Gleiter pressed iron particles with a diameter of 6nm in situ under high vacuum conditions, and sintered them to obtain nanocrystalline blocks, thus entering a new stage in the research of nanomaterials.
In July 1990, the first International Conference on Nanoscience&Technology was held in the United States, officially declaring nano material science as a new branch of material science.
Since the advent of nano particle materials in the 1970s, the research connotation and characteristics can be roughly divided into three stages:
The first stage (before 1990): mainly exploring the preparation of nano particle powders or synthetic blocks of various materials by various methods in the laboratory, studying the methods of evaluation and characterization, and exploring the special properties of nano materials different from ordinary materials; The research objects are generally limited to single materials and single-phase materials, which are generally called nanocrystalline or nano phase materials internationally.
The second stage (1990-1994): people focus on how to use the physical and chemical properties of nanomaterials to design nanocomposites. The synthesis and physical property exploration of composites once became the leading direction of nanomaterials research.
The third stage (since 1994): nano assembly system and nano structured material system synthesized by manual assembly are becoming the new hotspot of nano material research. Internationally, such materials are called nano assembly material systems or nanoscale pattern materials. Its basic connotation is that nano particles and their nanowires and tubes are used as basic units to assemble and arrange a system with nano structure in one-dimensional, two-dimensional and three-dimensional space.