A brief history of carbon nanotubes
Carbon nanotubes: Many people will be unfamiliar with this name. In fact, carbon nanotubes are also a type of carbon material. They can be generally understood as a tubular structure made of graphitized carbon atoms, single or multi-layer curled. The diameter of carbon nanotubes can be as small as nanometers, but their length can reach several meters, just like "a slender hair."
However, although carbon nanotubes are extremely small in size, their physical properties are extremely hard-core. According to Li Qingwen, a researcher at the Chinese Academy of Sciences, carbon nanotubes are 100 times stronger than steel of the same volume. Therefore, carbon nanotubes are also regarded as the strongest and hardest materials that humans can currently create. In practical applications, carbon nanotubes are also called universal materials because of their excellent electrical and thermal conductivity properties. In many subdivisions such as integrated circuits, batteries, and sensors, carbon nanotubes have broad application prospects.
Since Japanese physicists started research on carbon nanotubes in 1991, the international exploration of this new material has been going on for 30 years. Domestic leading companies and scientific research teams have also achieved many breakthroughs in the field of carbon nanotubes through continuous research and development and efforts, and "are already at the world's leading level in some fields."
In the 30 years since the discovery of carbon nanotubes, my country's research level has basically kept pace with the world's advanced level, and is leading the world in some fields. Carbon nanotube conductive agents have changed the situation of my country's lithium battery companies relying on imported conductive agents; carbon nanotube films have been successfully used in high-end outdoor thermal clothing and medical rehabilitation industries; integrated circuits and display backplane drive devices based on semiconductor carbon nanotubes Recently, the carbon nanotube conductive agent developed by the largest carbon nanotube production company in China has changed the situation of my country's lithium battery companies relying on imported conductive agents. Since their discovery, carbon nanotubes have sparked a research boom around the world. In recent years, the world has accelerated the exploration of ways to implement carbon nanotube technology, and related technological breakthroughs have continued.
As the most important element of life, "carbon" has always played a pivotal role in the evolution of life and energy supply. In 1985, the C60 with a "football" structure attracted the attention of the world as soon as it was discovered. In 1991, Japanese physicist Sumio Iijima observed carbon nanotubes in carbon materials prepared by the arc method, which started a boom in carbon nanotube research. Carbon nanotubes are like slender hairs, their lengths can reach meters and their diameters can be as small as nanometers. How are such slender nanotube-like structures prepared?
The carbon nanotubes first discovered by Sumio Iijima were produced by the arc discharge method. Now, carbon nanotubes have developed various preparation methods such as laser ablation, chemical vapor deposition (CVD), and solid-phase pyrolysis. Among them, the CVD method is widely used because of its low cost, good controllability, and easy large-scale preparation. As an important member of the nanocarbon material family, carbon nanotubes are known as "universal substrates" for their excellent mechanical, electrical and thermal properties. They are widely used in structural and functional integrated composite materials, battery electrodes, integrated circuits, sensor devices, and electronics. Heating devices and other fields have huge application prospects. Smalley, the 1996 Nobel Prize winner in Chemistry and the discoverer of fullerene, believes that carbon nanotubes are the strongest, stiffest, and hardest materials that can be made, and they are also the best conductors of heat and electricity. .
Implementation in practice
In terms of basic research on carbon nanotubes, the Peking University team has synthesized carbon nanotubes with controllable conductivity and unichiral carbon nanotubes. He has made important contributions in synthesis and separation. In terms of carbon nanotube applications, the Tsinghua University team has made great achievements in the macro-preparation of carbon nanotubes, high-strength carbon nanotube fibers, and carbon nanotube conductive additives. In 2013, the world’s smallest “computer” was born with parallel-arranged single-walled carbon nanotubes as its main components. In the past two years, the performance and size of carbon nanotube electronic devices have been broken through again and again.
Carbon nanotubes, known as "black gold", have been predicted by scientists to become one of the miraculous materials that will "completely change the 21st century". The use of conductive agents in lithium batteries is just the tip of the iceberg in the industrialization of carbon nanotubes.
As a national strategic emerging material, carbon nanotube materials are also widely used in conductive plastics, lightweight high-strength composite materials, broadband lightweight electromagnetic shielding, impact protection, smart materials, electronic devices, etc. Among them, the market prospects of heating films, conductive plastics, composite materials and other materials based on carbon nanotubes are also getting better and better.
There are hard nanometers and soft nanometers
We are all familiar with monitors; but can you imagine that they can be worn on the body? Ultra-thin monitor? The display fabric presents a unique overlapping structure, which is composed of interlaced luminous warp threads and conductive weft threads. Under the excitation of the electric field, the electrodes and the luminescent layer can achieve effective light emission by virtue of physical overlap.
Nanotechnology is one of the most important frontier science and technology fields in the 21st century. It plays a leading role in the economic and social development of countries around the world, and has a profound influence on the fields of information, biology, medicine, energy, environment, aerospace and national security. all have important impacts. In order to comprehensively enhance my country's nanotechnology innovation capabilities, the National Key Research and Development Program has established a key project on "nanotechnology". Currently, this project has achieved a number of important results.
From blurry to clear, from monochrome to color, from bulky to thin... In recent decades, displays, as an important output end of electronic devices, have been continuously updated and iterated, including the original cathode ray tube display, liquid crystal Displays, organic light-emitting diode displays, and the current flexible film displays have made great progress. Have you ever imagined wearing a monitor on your body? Integrating device functions, textile methods, and fabric shapes, we can browse and consult, send and receive messages, and make event memos on the clothes we wear... This is a direction that researchers have been exploring in recent years.
However, how to effectively integrate display functions into electronic fabrics while ensuring the softness, breathability, moisture conduction, and adaptability to complex deformation of the fabric is a challenge faced by the field of smart electronic fabrics. A big problem. Recently, with the funding of the "Nano Technology" key project of the National Key Research and Development Program, a research team from Fudan University independently developed a fully flexible fabric display system: the journey of exploring fabric display is by no means a smooth road. In 2009, the team proposed the research idea of ??combining polybutadiyne with oriented carbon nanotubes to prepare new electrochromic fibers. However, electrochromism is only visible during the day and cannot be effectively applied at night, greatly reducing the use time domain.
In 2015, the team made a breakthrough in coating methods, successfully solved the problem of uniform film formation of the first-yoke polymer active layer on the surface of high-curvature fiber electrodes, and proposed and realized the development of fiber polymers. photoelectrochemical cells and achieve different light-emitting patterns by weaving them into fabrics. However, this method also has limitations. The number of patterns displayed through luminescent fiber weaving is very limited, and it is impossible to achieve controllable display based on luminescent pixels in flat displays. How to build a programmable array of luminescent dots on soft fibers with a diameter of only tens to hundreds of microns is a major problem that plagues the team and even this field.
What gives fabrics its display properties? What is its internal structure? Under the excitation of the electric field, the electrode and the luminescent layer can achieve effective luminescence by virtue of physical overlap. This method can unify the preparation of the luminescent device and the fabric weaving process. Using industrial weaving equipment, a 6-meter-long, 0.25-meter-wide, and The luminous fabric has about 500,000 luminous points, and the minimum distance between the luminous points is 0.8 mm, which can initially meet the resolution requirements of some practical applications. By replacing the luminescent materials, multi-color luminescent units can also be realized to obtain colorful display fabrics.
Advanced technology, body-worn display
Compared with traditional flat-panel light-emitting devices, the diameter of the luminescent fiber can be accurately between 0.2 mm and 0.5 mm. Control and control establish its ultra-fine and ultra-soft characteristics. Clothes woven from this material can closely fit the irregular contours of the human body and are as light and breathable as ordinary fabrics, ensuring good wearing comfort.
Subsequently, practical application requirements also followed. The team's research found that when fibers with high curvature surfaces come into contact with each other, uneven electric field distribution will be formed in the contact area. Such an electric field is not conducive to the stable operation of the device during deformation. In real life, the clothes you wear will inevitably have bumps and bumps, and they also need to be cleaned daily.
How can the display fabric adapt to changes in the external environment, even resist external forces such as repeated friction, bending, and stretching, and ensure the stability of light emission?
The team worked hard on the mechanical properties of the conductive fiber weft and prepared a highly elastic transparent polymer conductive fiber through melt extrusion. During the weaving process, due to the action of linear tension, the area of ??the fiber in contact with the luminous fiber undergoes elastic deformation and is fixed by the interlocking structure of the fabric.
Providing good application prospects
In addition to display fabrics, Peng Huisheng’s team also realized a functional integrated system with photovoltaic fabrics, energy storage fabrics, touch sensing fabrics and display fabrics based on the weaving method , making it possible to integrate multi-functional fabric systems such as energy conversion and storage, sensing and display. The system shows good application prospects in the fields of Internet of Things and human-computer interaction, such as real-time positioning, intelligent communication, and medical assistance.
In field work scenarios such as polar scientific expeditions and geological exploration, location information can be displayed in real time with just a few taps on clothing, and map navigation is guided by "clothes" ; Wearing a monitor on the body, people with language impairments can use it as a tool for efficient and convenient communication and expression... These scenes that originally existed in imagination may enter people's lives in the not-too-distant future.
(The content of the article comes from the Internet)
Extra: About the manufacturing of monitors
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