Interaction of Carbon Nanotube with Ethylene Glycol-Water Binary Mixture: A Molecular Dynamics and Density Functional Theory Investigation

Classical molecular dynamics (MD) simulation has been carried out on model systems composed of ethylene glycol (EG) and carbon nanotube (CNT) in water (WAT) medium to gain insight into the interaction between them. The analysis of the MD results reveals that the EG molecules aggregate around CNT expelling water molecules due to the hydrophobic-hydrophobic interaction. Hydrogen-bonding (H-bonding) interaction between two EG molecules increases in the presence of CNT. Further, the presence of CNT decreases the solubility of EG in water. The analysis of the dihedral angle of EG reveals that the CNT induces conformational changes in EG. Specifically, a small fraction of the gauche form of EG is converted into trans. In addition, electronic structure calculations have also been carried out on model systems to quantitatively determine the binding energy (BE). The M05-2X/6-31+G** level calculations on the model systems show that the BE of CNT-WAT and CNT-EG ranges from 11.76 to 17.78 kJ/mol. It is interesting to note from the electronic structure calculations that the BE of trans EG with CNT is more than that of gauche EG with CNT in accordance with the findings from the MD simulation.