Adsorption of Evans blue and Congo red on carbon nanotubes and its influence on the fracture parameters of defective and functionalized carbon nanotubes studied using computational methods

摘要

This work addresses the problem of the modification of mechanical parameters of carbon nanotubes as a result of Congo red and Evans blue adsorption, functionalization of the nanotubes surfaces by carboxyl groups and generation of surface defects. The studies were also focused on the quantum chemical analysis of the effects of Evans blue adsorption on the properties of the nanotubes. We found that Evans blue is rather physisorbed than chemisorbed and it does not significantly affect the electronic state of the nanotubes. The molecular dynamics studies led to the conclusion that the nanotube chirality affects the fracture parameters substantially but the presence of the adsorbed Congo red/Evans blue mixture has only minor effect for the zigzag nanotubes. The effect is slightly bigger for the defective armchair nanotubes and significant fluctuations of the failure strain was observed. However, non defective armchair ones are also not sensitive to the adsorption of dyes. The presence of surface functionalization was generally found as negligible. The only exception were defective armchair nanotubes for which small changes (+/- 5%) were found for the carboxylated nanotubes.