Hydrophilic behavior of Graphdiyne Nanotube from SCC-DFTB and Car-Parrinello Molecular Dynamics Simulation

Graphdiyne nanostructures have been considered due to the predictions of quantum calculations regarding the occurrence of special electronic and structural features before the synthesis of these structures. We study the hydrophobic/hydrophilic behavior of GDNT using molecular dynamics simulations. The energetics of the carbon-water interface are mainly dispersive but in the present study augmented with a carbon quadrupole term acting on the charge sites of the water. The simulations indicate that this contribution is negligible in terms of modifying the structural properties of water at the interface. Simulations of GDNTs in water display a wetting and drying of the interstice between the GDNT depending on their initial spacing. Thus, initial tube spacing’s of ۷ and ۸Å resulted in a drying of the interface whereas spacing of>۹ Å remain wet during the course of the simulation.The results showed that water molecules do not enter into small-diameter nanotubes and aggregate in the walls, and this is due to the hydrophobic property of smaller carbon nanotubes, while the larger nanotubes do not show this feature. Also, the positive effect of pressure at the constant temperature on the aggregation of water molecules inside Graphdiyne nanotubes (۲,۰) was observed.