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Preparation and Property of Electric Compesite Basic CNTs

Author: FengChao
Tutor: MoZunLi
School: Northwest Normal University
Course: Inorganic Chemistry
Keywords: Carbon Nanotubes Polyaniline Nanocomposites Conductivity Fluorescence
CLC: TB383.1
Type: Master's thesis
Year: 2010
Downloads: 156
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Abstract

Since been found since 1991, carbon nanotubes (carbon nanotubes, CNTs) because of their unique mechanical properties, chemical properties, thermal and electrical properties and receive widespread attention, is considered in many fields are potential new nanomaterials. Carbon nanotubes have a unique one-dimensional tubular structure has a large aspect ratio, the higher the specific surface area, but because of their inherent insolubility, making it difficult in a solution of carbon nanotubes in the polymer matrix or a better dispersion, thus largely restricted in their composite applications in the field. Currently used widely modification method is to use carbon nanotubes mixed acid treatment, carboxyl groups introduced on the surface of carbon nanotubes, and use it as the active grafting point. This method can effectively overcome the inertia surface of the tube, the use of chemical bonding such a way that the polymer complex organic molecules. But this method also obvious deficiencies in mixed acid treatment process, although can effectively introduce carboxyl functional groups, but will inevitably destroy the original CNTs perfect geometry, resulting in the surface of the tube defects, and even carbon nanotubes will be truncated to a length shorter tubular structure, which is bound to weaken the carbon nanotubes could have a variety of excellent performance. This physical method using a modification of the carbon nanotubes, carbon nanotubes retain the structure and properties is not destroyed, to obtain a more satisfactory result. The experiment consists of three parts: first, the use of concentrated nitric acid under the conditions of the ultrasonic MWNTs were purified to remove the impurities, the carbon nanotube while maintaining its structure is not destroyed. Stirred at room temperature using the method of the purified carbon nanotubes with Eu (Ⅲ) -1,10-phenanthroline complexes were compounded by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) on the composite structure and surface morphology analysis, the results showed that Eu (Ⅲ) -1,10-phenanthroline complexes uniformly coated on the surface of carbon nanotubes. Elementary analysis, Eu (Ⅲ) ions and 1,10-phenanthroline in a 1:1 ratio ligand, the system inputs complexes are almost entirely carbon compound occurs, very high yields can be obtained a composite material. Shows the fluorescence spectra of Eu (Ⅲ) -1,10-phenanthroline complexes of a characteristic spectrum of migration occurred, and decreased intensity of the emission spectrum, which is consistent with the literature. This is due to two phenomena resulting complexes and carbon exists between the result of photoelectric conversion. In addition, its conductivity analysis, the results showed that the composite did not cause changes in the proportion of composite conductive properties change significantly, has been stable at 7S/cm fluctuations. Thermal gravimetric analysis shows the thermal stability of the composite material line than Eu (Ⅲ) -1,10-phenanthroline complexes. Second, the use of in situ polymerization, in the first part of the obtained composite material as filler, and make the polyaniline compound, to obtain a three-phase composite material. Use ETIR and SEM material composition and surface morphology were characterized, the results show the success of polyaniline coated on CNTs / Eu (Ⅲ) -1,10-phenanthroline surface. Fluorescence emission spectra show the composite strength is weak, which is due on the one hand between the complexes and the carbon tube kept the role of this photoelectric conversion, on the other hand may be due to the excitation and emission spectra of polyaniline, there are certain absorption , resulting in the weakening of the emission spectrum. TGA shows the thermal stability of the composite material than pure polyaniline improved to a great extent. Third, polyethylene glycol-400 as an emulsifier, under stirring at room temperature and the purified carbon nanotubes of composite silver nanoparticles. Transmission electron microscopy (TEM) showed that the black spots on the surface of carbon nanotubes showed the success of composite silver nanoparticles on the surface of the carbon tube. This composite material as filler, using the in situ polymerization, and make the polyaniline composite, by infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) on the composite composition and structure were characterized, the results show the success of polyaniline the surface of the carbon nanotubes composite and carbon tubes are completely covered included. When CNTs / Ag filler is added in an amount of 0.35% of the value of the filter field to achieve infiltration. Conductivity of the material from 2.15 S / cm up 10.14 S / cm. Thermal gravimetric analysis shows the thermal stability of the composite material is superior to pure polyaniline.

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