Disperse systems with the multi-walled carbon nanotubes

The functionalization of the surface of multi-walled carbon nanotubes by polar groups, as well as the influence of the type and size of particles of nanocarbon materials on the stability of the disperse system have been investigated. The formation of disperse systems of multi-walled carbon nanotubes with acrylic monomers has been studied. Physicochemical methods of analysis have been used to investigate the structure and properties of multi-walled carbon nanotubes after various ways of modifying their surface. Carbon nanotubes tend to form agglomerates, which makes it difficult to introduce them into composite materials, including those based on polymer matrices. To give the necessary technological properties (compatibility with the matrix of the material, the formation of stable dispersion), they are modified in various ways. Carboxylation of the surface leads to better compatibility of multi-walled carbon nanotubes with polar solvents or monomers, hence the multi-walled carbon nanotubes functionalized by grafting polar carboxyl groups on the surface and forming a stable dispersion system with acrylic monomers are the most promising in terms of processing properties for dispersion. Treatment with chemical reagents leads to reduction in the diameter of nanotubes due to removal of graphene layers, the surface of the tubes becomes microdispersed at the same time. The formation of a stable disperse system is affected by the type of carbon nanotubes, the content of tubes in the monomer, and the viscosity of the dispersion medium. Reducing the size of particles leads to greater stability of the disperse system, but this increases the specific surface area and the ability of carbon nanotubes to agglomerate, which leads to a decrease in the stability of the system; therefore, ultrasonic treatment is required for several minutes to obtain the disperse system. The dispersion time for obtaining a stable system depends both on the percentage of the multi-walled carbon nanotubes in the monomer and on the structure of the monomer. When a more viscous polymer solution is used, namely polymethyl methacrylate in its own monomer, the dispersion is stable. In this case, the process of thermosetting of methyl methacrylate proceeds without deviations and the nanotubes are evenly distributed in the resulting polymer.