Feb 12, 2025
Company News
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Single-Walled Carbon Nanotubes (SWCNTs) are seamless tubular structures curled from single-layer graphene sheets. The diameter is only 1-2 nanometers and the length can reach the micron level. This one-dimensional nanomaterial shows extraordinary mechanical, electrical and thermal properties due to its unique atomic arrangement:
Mechanical properties: Young's modulus is as high as 1 TPa, and its tensile strength is 100 times that of steel.
Electrical properties: The conductivity is better than copper, and metallic or semiconductor properties can be achieved through chiral regulation.
Thermal properties: The thermal conductivity is twice that of diamond, and it is an ideal heat dissipation material.
Compared with multi-walled carbon nanotubes (MWCNTs), single-wall structures have more application potential in high-end fields due to their few defects and higher purity.
Currently, the mainstream preparation methods include chemical vapor deposition (CVD), arc method and laser evaporation method. The specific formulas are as follows:
Process: Deposit a catalyst (such as Fe and Co doped non-metallic elements) on the substrate, pass into a carbon source gas (such as methane), and crack and grow at high temperature.
Optimization conditions:
Temperature: 700-1000℃;
Catalytic: Doped with non-metallic elements such as P, S, and the control particle size is 5-30 nm;
Carbon source: The liquid carbon source evaporates more uniformly and has higher purity.
Advantages: Strong controllability, suitable for large-scale production; Disadvantages: High equipment cost, and process parameters need to be accurately controlled.
principle: High temperature is generated by discharge of graphite electrodes, and carbon vapor is generated and condensed into SWCNTs.
Features: The product has high purity, but it consumes a lot of energy, making it difficult to produce continuously.
process: Use laser to bombard the graphite target containing catalyst, and deposit it after evaporation to form SWCNTs. Advantages: The product is chirally controllable; Disadvantages: The equipment is expensive and the output is low.
Taking a patented technology as an example, the specific steps are as follows:
1. Device design: The reaction chamber is divided into two chambers, with a liquid carbon source (such as ethanol) injected at the bottom, and the top rotation shaft drives the substrate to rotate.
2. Catalyst treatment: Deposit a sulfur-doped metal catalyst precursor (such as Fe-S) on the substrate, with a thickness controlled at 5-30 nm.
3. Reaction process:
Heat it until the liquid carbon evaporates under the protection of inert gas;
heats to 900℃ and a hydrogen reduction catalyst is introduced;
The rotation shaft rotates at 30 r/min to promote uniform adsorption of the carbon source and formation of a helical structure.
4. Product collection: The single-walled tube grows to a certain length and breaks away from the substrate, with a purity of more than 95%.
Key innovation: Through rotation of the shaft and non-metal doping, controllable growth of the helical structure is achieved, and the problem of uneven morphology of traditional methods is solved.
1. Problem 1: The product contains impurities or multi-wall structure
Reason: Catalyst agglomeration or uneven carbon source concentration.
Solution: Optimize the dispersion of the catalyst, adopt a liquid carbon source and control the evaporation rate.
2. Question 2: SWCNTs dispersion
cause: High surface energy leads to reunification.
Solution: Functionalized treatment (such as PEG modification) or the use of dispersants.
3. Question 3: High production cost
Solution: Develop continuous CVD equipment to improve catalyst utilization.
Tian Donglong's research team has developed a new equipment and purification process that can continuously purify carbon nanotubes at lower temperatures. Compared with traditional carbon nanotube purification technology, the continuous carbon nanotube purification technology has high purification efficiency, good purification effect and low energy consumption. It is a new and efficient purification equipment and purification process. [1] Zhang Xinyu's research team found that GO has a huge specific surface area, strong water absorption and excellent mechanical properties; the surface contains a large number of oxygen-containing functional groups such as hydroxyl groups (-OH) and carbonyl groups (C=O), which are easy to mix with other matrix or matrix materials to prepare composite materials. [2]
Li Min's research team developed SWCNT photosynaptic transistors based on silicon substrates and flexible substrates, explored the synergy of photoelectric signals and the simulation of complex synaptic functions, elucidated the generation mechanism of photoelectric synaptic plasticity, and built a SWCNT CMOS inverter with ultra-low power consumption. [3]
Kong Jiahua's research team discussed a variety of techniques for preparing such composite materials, and analyzed in detail how the addition of carbon nanotubes changes the properties of epoxy resins. The specific impact of carbon nanotubes on the mechanical properties of epoxy resins was particularly emphasized. [4]
Based on the sol-gel method, Wang Xiaolan's research team prepared different proportions of multi-wall carbon nanotube modified silicone resin (CNT/OSR) aerogel and needle-punched quartz fiber-reinforced CNT/silicon resin aerogel (QF/SC) composite materials to explore the influence of CNT content on the microstructure, heat resistance and wave absorption properties of silicone aerogel and its composite materials. The research results show that CNT after physical modification shows good compatibility with silicone resin and builds microconductive and thermal conductivity channels; the thermal stability of the resin has been significantly improved after modification. When the mass fraction of CNT is 15 wt%, the weight loss is 10 wt% corresponding to the temperature. [5]
Li Ling's research team is exploring its feasibility as biological scaffolds and drug carriers at the cellular and animal levels, respectively. In addition, new methods for gold nanoparticles to modify the surface of SWCNTs are explored to study their feasibility for near-infrared thermal therapy.
