We have performed molecular dynamics (MD) simulations to study the thermodynamics, structure, and dynamical behavior of 1-ethyl-3-methylimidazolium hexafluorophosphate [emim] [PF 6 ] during the melting process inside carbon nanotubes (CNTs) with different radii. Our structural results indicate the layering behavior for the IL inside the zigzag and armchair CNTs with the local maximums in the densities close to the CNT walls. The sharp and intense peaks are also observed at low temperature.However, as the temperature increases, the peaks related to the layer structure near the CNT wall become broader and less intense. It is also shown that the average number of hydrogen bonds decreases as the temperature increases. The internal energy also increases slightly with increasing temperature, followed by a dramatic jump. The temperature at this jump merely corresponds to the starting melting temperature, and another turning point in the energy curve corresponds to the entirely molten temperature, observed to be nearly 500 and 900 K, respectively. It is also shown that the diffusion coefficient increases as the temperature increases and a dramatic increase in the diffusion of the IL molecules occurs at the same temperature as the jump in total energy and thus marks the melting transition without ambiguity.
Molecular dynamics simulations are used to study CO adsorption on Ag nanoclusters ranging from 38 to 500 Ag atoms, supported on carbon nanotube. Each nanocluster was simulated under various pressures of CO gas at different temperatures. The absolute value of enthalpy of adsorption was calculated for all of the nanoclusters in constant coverage which is increased sharply by decreasing cluster size. This increasing trend with coverage reaches a maximum around 0.75 ML for Ag 108 . Also, the structural changes are irreversible in such a way that by gradually decreasing the pressure to zero, the nanocluster geometry is not reversed to its initial structure in vacuum conditions. It was found that structural irreversibility increases with the size. Also, the difference between diffusivity of Ag nanoclusters in vacuum and CO atmosphere increases with the size.
In this work, liberation of cisplatin molecules from interior of a nanotube due to entrance of an Ag-nanowire inside it was simulated by classical molecular dynamics method. The aim of this simulation was investigation on the effects of diameter, chirality, and composition of the nanotube, as well as the influence of temperature on this process. For this purpose, single walled carbon, boron nitride, and silicon carbide nanotube were considered. In order for a more concise comparison of the results, a new parameter namely efficiency of drug release, was introduced. The results demonstrated that the efficiency of drug release is sensitive to its adsorption on outer surface of the nanotube. Moreover, this efficiency is also sensitive to the nanotube composition and its diameter. For the effect of nanotube composition, the results indicated that silicon carbide nanotube has the least efficiency for drug release, due to its strong drug-nanotube. Also, the most important acting forces on drug delivery are van der Waals interactions. Finally, the kinetic of drug release is fast and is not related to the structural parameters of the nanotube and temperature, significantly.
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