Carbon nanotubules: morphology and properties

Abstract

The morphology and sorption characteristics of carbon nanotubules of different types were investigated. Experiments were conducted on separating individual carbon nanotubules from agglomerates with mechanical, electric arc, and ultrasound effects. Fractionation of suspensions of nanotubules combined with ultrasound treatment is the most promising. The effect of the chemical composition of the surface of carbon nanotubules on their electrical properties was demonstrated. Composite film materials with resistivity of 15 . 10 6 at a 0.5 wt. % degree of filling were obtained from fluoroplastic F-2M and carbon nanotubules CNT-6.Since their discovery by Iijima in 1991, carbon nanotubules (CNT) have drawn the attention of scientists working in different areas of science and engineering. There are now many varieties of carbon nanotubules and nanofibres that differ in structure, properties, and areas of application. Two basic types of nanotubules are usually distinguished: single-layer and multilayer carbon nanotubules. Model images of these CNT are shown in Fig. 1.Carbon nanotubules have a number of interesting properties due to the defined structure: high mechanical strength, thermal and electrical conductivity, chemical stability, etc.[1]. Their internal volume can be filled with different substances, for example, hydrogen, drugs, and metals. For this reason, nanotubules can be unusual filled template materials or "nanoreactors" [2,3]. The surface of carbon nanotubules and nanofibres can easily be chemically modified (functionalized) to improve their dispersibility in different solvents and increase the sorption properties [4]. The comparative characteristics of different carbon materials are reported in Table 1 [ 5,6].Due to their unique properties, carbon nanotubules are ideal disperse fillers for fabricating light composite materials. Despite the important progress in production of CNT, their structural parameters are critical moments for each concrete area of application. A difference in the structure inevitably results in a difference in the properties of nanoparticles, which is manifested in the wide range of criteria in evaluating them (see Table 1). In selecting CNT, it is necessary to consider a multitude of criteria on the macro-and nanolevel: homogeneity, purity, chirality, specific surface area, strength, presence of defects and functional groups on the surface. For use in electronics, the presence of defects, heteroatoms, functional groups, or adsorbed compounds on the surface of CNT is an extremely important negative factor, since it decreases the conductivity and effectiveness of ballistic charge transport [7,8]. In catalysis, the basic parameters which must be controlled are the specific surface area, defectiveness, and chemical state of the surface [9]. For using CNT in medicine, it is necessary to rigorously monitor the presence of contaminants and functional groups, since these factors affect the biocompatibility and cytotoxicity of the nanoparticles [10-12].We report data characterizing the propertie...