Selective Dispersion Of Polyimide - Based Polymers On Single - Walled Carbon Nanotubes

The present available technique yielded single wall carbon nanotubes(SWNTs)with different diameters and varying helix angles. From the viewpoint of conductivity,they are all mixtures of metallic and semiconducting SWNTs. In order to achieve the effective separation of the two species in the liquid phase, it is necessary to disperse the bundles of SWNTs into individual ones, and then makes it possible to isolate the monodisperse SWNTs with a single conductivity, laying the material foundation for their applications in electronics, optics and magnetism.The main research contents of this dissertation are as follows:(1) The soot containing SWNTs are by prepared by an improved arc discharge method. Individual SWNTs with high purity and good stability are obtained through successive heat treatment, prolonged hydrochloric acid immersion, surfactant assisted dispersion and ultracentrifugation.(2) Five triphenylamine polyimides with varying main chains are synthesized and applied to the selective dispersion of the arc-discharged SWNTs. The experimental results show that the polyimides show selective dispersion ability towards semiconducting SWNTs. Their difereneces in the selective dispersion ability towards semiconducting SWNTs are clarified from the π-π conjugating effect and the flexibility of the polymer backbone for the above five triphenylamine polyimides.(3) Two polyimides with short side chains are synthesized and applied to the selective dispersion of the arc-discharged SWNTs. The experimental results show that the polyimide with longer side chain has better selectivity to the semiconducting SWNTs than the one with shorter side chain.(4) The synthesized polyimide polymers are graded using the gel column chromatography technology. The experimental results show that the polyimide with higher polymerization degree has better selectivity towards the semiconducting SWNTs than the one with lower polymerization degree.