DISPERSION OF CARBON NANOTUBES IN ORGANIC SOLVENTS DUE TO HIGH FREQUENCY SONICATION
Аndriy Nadtochiy, Oleg Korotchenkov
Faculty of Physics, Taras Shevchenko National University of Kyiv, Kyiv 01601, Ukraine
Despite carbon nanotubes (CNTs) are promising for numerous applications, they are relatively insoluble in common solvents, which makes their separation difficult. Here, CNTs were effectively dispersed in organic solvents using a 400 kHz ultrasound. The degree of dispersion is quoted by measuring the total impedance of the solution poured into a cell. Main results can be understood in terms of the transfer function for the equivalent circuit. The descending part of the impedance vs frequency curve illustrates the capacitive conductance. Instead, if the curve remains unchanged with frequency, the resistive conductivity prevails in a given frequency range. It is obseved that chloroform and methylene chloride are much better for CNT dispersion than alcohols. Sonication of these solutions dramatically decreases their impedance (by 2.5 orders of magnitude) making it nearly conductive, which presents a major improvement over alcohols in the uniform dispersion of CNTs. The results can be explained by the fact that the sonication process offers the solubilizing effects by changing the solvent characteristics and also the chemical modification of CNTs themselves coming from the cavitation, which entails bubble formation, growth and collapse in the solution.