Study On Surface Treatment And Dispersion Of Carbon Nanotubes

Carbon nanotubes have unique structure and excellent properties,but the high aspect ratio and the inability to dissolve in most solvents and the mutual attraction between carbon nanotubes make carbon nanotubes agglomerate together,which affects the properties and the application of carbon nanotubes.Carbon nanotubes are dispersed in three steps: wetting,dispersion and stabilization.The thesis focuses on how to improve the wettability of carbon nanotubes in water and N-methylpyrrolidone.The thesis explores the effects of ultrasonic parameters and the addition of different dispersants on the dispersion of carbon nanotubes.The dispersion stability of carbon nanotubes is evaluated by UV-visible spectrophotometer and scanning electron microscope.The thesis also studies the method for preparing high-concentration carbon nanotubes.According to the experimental results,it is found that the selected carbon nanotubes had the highest thermal stability and the best wettability in water after reflux treatment with a 3:1 volume ratio of sulfuric acid and hydrogen peroxide.Ultrasonic treatment will damage the carbon nanotube.When the ultrasonic power is selected as 8kw and ultrasonic time is selected as 5 minutes carbon nanotubes can be stably dispersed.Surfactants can effectively disperse carbon nanotubes in water,and the ability of surfactants with the same structure and hydrophilic groups to disperse carbon nanotubes increases as the chain length of the hydrophobic group increases.When the surfactant contains benzene ring,the dispersibility of the surfactant to the carbon nanotubes can be improved.However,the ability to disperse carbon nanotubes does not increase as the number of benzene ring structures increases.Among the dispersants used in the experiment,Triton X-405 dispersed carbon nanotubes best.Carbon nanotubes refluxed with hydrogen peroxide solution exhibited the best wettability in the N-methylpyrrolidon.Non-ionic surfactants and dispersants containing amide bonds can effectively disperse carbon nanotubes in N-methylpyrrolidone,and Triton X-405 also exhibits the best ability to disperse carbon nanotubes in N-methylpyrrolidone.In the preparation of high concentration carbon nanotube slurry,pre-mixing and grinding is an important means of large-scale production of carbon nanotube slurry.According to this method,5wt% carbon nanotube slurry can be prepared.