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.

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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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Au@void@AgAu yolk-shell nanoparticles with different morphologies were studied by classical molecular dynamics simulation. The results indicated that all of simulated yolk-shell nanoclusters with ∼3.8 nm size and different morphologies are unstable at room temperature, and collapse of the shell atoms into the void space completely fills it and creates more stable Au@AgAu core-shell structures. Also, it was observed that thermodynamic stabilities of the created core-shell structures strongly depend on the morphology of nanocluster, for which competition between strain and surface energy effects plays the key role in this phenomenon. Within this competition, strain effect is dominant and helps the stability of the created core-shell structure. Herein, the icosahedral nanocluster with the lowest strain effect exhibits the highest thermodynamic stability. By comparing the simulation results with experimental data, it was concluded that the essential factor that controls the stability of these nanoparticles is their size.

We have studied the heating and cooling processes of CuN nanoclusters encapsulated in CNTs with different diameters and chiralities in the range of 100-1700 K. We have investigated all of the possible effects: the effects of the nanocluster size, CNT diameter, and CNT chirality on the thermodynamic, structural, and dynamic properties during the melting process. Our thermodynamic results showed that the melting temperatures of the confined nanoparticles tend to increase with the nanoparticle size. Our energy results also showed that the melting temperature of the nanocluster decreases upon decreasing the CNT diameter, which is due to the greater nanocluster-CNT wall interactions in the smaller nanotube which make the cluster to expand more easily on the interface. The results also showed that the encapsulation of the nanocluster in the zigzag CNT has lower energy values than the armchair one, which is due to the greater interaction of the nanocluster and the zigzag CNT wall. We have also recognized a hysteresis in the course of the cooling process, which can be due to the fact that the nanoclusters and the nanotube make a coherent interface structure with more stability. Using the radial distribution function, it has been shown that the structural change with temperature is irreversible. Our dynamical results indicated that the bigger nanocluster has slower dynamics than the smaller cluster. It is also shown that the nanocluster on the smaller and zigzag CNTs has slower dynamics than the bigger and armchair tubes.

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