Phase transition study of confined water molecules inside carbon nanotubes: Hierarchical multiscale method from molecular dynamics simulation to ab initio calculation

Javadian, Soheila; Taghavi, Fariba; Faramarz, Yari; Hashemianzadeh, Seyed Majid

doi:10.1016/j.jmgm.2012.05.009

Cited by 11 publications

(5 citation statements)

References 71 publications

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“…Therefore, MD simulations have been used as the first step for the ab initio calculations. [21] The correlation function obtained from the MD simulations gives the spectrald ensity by Fouriert ransform. The spin-lattice relaxation time is obtained by inverse proportion of the correlation function.…”

Section: Resultsmentioning

confidence: 99%

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Fast Water Relaxation through One‐Dimensional Channels by Rapid Energy Transfer

et al. 2016

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Water in carbon nanotubes is surrounded by hydrophobic carbon surfaces and shows anomalous structural and fast transport properties. However, the dynamics of water in hydrophobic nanospaces is only phenomenologically understood. In this study, water dynamics in hydrophobic carbon nanotubes is evaluated based on water relaxation using nuclear magnetic resonance spectroscopy and molecular dynamics simulations. Extremely fast relaxation (0.001 s) of water confined in carbon nanotubes of 1 nm in diameter on average is observed; the relaxation times of water confined in carbon nanotubes with an average diameter of 2 nm (0.40 s) is similar to that of bulk water (0.44 s). The extremely fast relaxation time of water confined in carbon nanotubes with an average diameter of 1 nm is a result of frequent energy transfer between water and carbon surfaces. Water relaxation in carbon nanotubes of average diameter 2 nm is slow because of the limited number of collisions between water molecules. The dynamics of interfacial water can therefore be controlled by varying the size of the hydrophobic nanospace.

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Section: Resultsmentioning

confidence: 99%

“…The ab initio calculations have severe limitations in the large systems, although those could be used to evaluate NMR spectra. Therefore, MD simulations have been used as the first step for the ab initio calculations . The correlation function obtained from the MD simulations gives the spectral density by Fourier transform.…”

Section: Resultsmentioning

confidence: 99%

Fast Water Relaxation through One‐Dimensional Channels by Rapid Energy Transfer

et al. 2016

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“…Understanding the structure, dynamics, and thermodynamic properties of water phases in CNTs at room temperature can be helpful in understanding phase transition in nanoscale confinement of water. In recent work, the nature of phase transition of water in nanoscale confinement has been questioned. − ,, Although several studies were performed to elucidate the nature of phase change in CNTs, most of them focused on the phase change with temperature, − and the spatial phase change (at room temperature, T = 300 K) in CNTs due to configurational entropy induced by confinement was not investigated in detail. − A systematic understanding of the effect of confinement on the complex spatial variation of the water phase and its properties, especially at room temperature, is currently lacking. Here, we show the existence of different phases of water in a single carbon nanotube at room temperature.…”

Section: Introductionmentioning

confidence: 99%

Existence of Multiple Phases of Water at Nanotube Interfaces

Farimani

Aluru²

2016

J. Phys. Chem. C

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Water, because of its anomalous properties, can exhibit complex behavior under strong confinement. At room temperature and pressure, water is assumed to exist in a single phase as a liquid under confinement (e.g., in a carbon nanotube). In this study, using extensive molecular dynamics simulations, we show the existence of multiple phases of water when water meets a nanotube surface under atmospheric conditions (T = 300 K, P = 1 atm). Vapor, high-density ice, and liquid water phases coexist in the region within ∼1 nm from the surface. Structure factor, entropy, pressure, viscosity, and rotational diffusion of water layers near the surface reveal substantial phase anomalies induced by confinement. We show the presence of a new high-density solid-state ice layer (ρ = 3.9 g/cm3) with rhombic structure coexisting adjacent to vapor and liquid water. The existence of multiple phases of water near an interface can explain, for example, the slip phenomena, self-filling behavior of a carbon nanotube, and fast transport of water.

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“…Fluorescence spectroscopic measurements and simulation studies seem to suggest drastic decrease of static dielectric constant (1 0 ) of bulk water upon confinement. [16][17][18][19] Confined water is found in biology such as in lipid bilayers, ion channels and protein cavities [20][21][22][23]; 'biological water' at protein surfaces [24]; in chemistry such as in fuel cells, [25] gels and reverse micelles [13,[26][27][28][29][30]; in technology such as in carbon nanotubes, [31][32][33] granular and porous materials, [34] etc. Computer simulations on the effects of confinement on structure and dynamics of binary liquid mixtures composed of asymmetric particles [35] have attempted to provide answers to some basic questions of this area.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen-bond dynamics of water in presence of an amphiphile, tetramethylurea: signature of confinement-induced effects

Indra

Biswas

2014

Molecular Simulation

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Various experimental and simulation studies have suggested that the presence of amphiphilic molecules in aqueous solutions substantially perturbs the tetrahedral hydrogen-bond (H-bond) network of neat liquid water. Such structural perturbation is expected to impact H-bond lifetime of liquid water. Tetramethylurea (TMU) is an example of an amphiphile because it possesses both hydrophobic and hydrophilic moieties. Molecular dynamics simulations of (water þ TMU) binary mixtures at various compositions have been performed in order to investigate the microscopic mechanism through which the amphiphiles influence the H-bond dynamics of liquid water at room temperature. Present simulations indicate lengthening of both water -water H-bond lifetime and H-bond structural relaxation time upon addition of TMU in aqueous solution. At the highest TMU mole fraction studied, H-bond lifetime and structural relaxation time are, respectively, , 4 and , 8 times longer than those in neat water. This is comparable with the slowing down of H-bond dynamics for water molecules confined in cyclodextrin cavities. Simulated relaxation profiles are multi-exponential in character at all mixture compositions, and simulated radial distribution functions suggest enhanced water -water and water -TMU interactions upon addition of TMU. No evidence for complete encapsulation of TMU by water H-bond network has been found.

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Phase transition study of confined water molecules inside carbon nanotubes: Hierarchical multiscale method from molecular dynamics simulation to ab initio calculation

Cited by 11 publications

References 71 publications

Fast Water Relaxation through One‐Dimensional Channels by Rapid Energy Transfer

Fast Water Relaxation through One‐Dimensional Channels by Rapid Energy Transfer

Existence of Multiple Phases of Water at Nanotube Interfaces

Hydrogen-bond dynamics of water in presence of an amphiphile, tetramethylurea: signature of confinement-induced effects

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