On the Consistency of the Exfoliation Free Energy of Graphenes by Molecular Simulations

Gotzias, Anastasios; Tocci, Elena; Sapalidis, Andreas

doi:10.3390/ijms22158291

Cited by 4 publications

(1 citation statement)

References 55 publications

(71 reference statements)

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“…It is with this motivation that we simulate the free energy of different carbon frameworks crossing hydrophobic-hydrophilic solvents [18,19]. Practicing with well-defined force fields (all-carbon solids, cyclohexane as the organic solvent, and SPC water) helps the formulation and execution of a sustainable workflow commited to free energy simulations [20][21][22][23][24][25]. The workflow is a precursor on an ongoing computational campaign investigating the binding affinities of such materials embedded in conjugated solvents with larger molecules such as polymers, surfactants, or lipids [26,27].…”

Section: Introductionmentioning

confidence: 99%

Umbrella Sampling Simulations of Carbon Nanoparticles Crossing Immiscible Solvents

Gotzias

2022

Molecules

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We use molecular dynamics to compute the free energy of carbon nanoparticles crossing a hydrophobic–hydrophilic interface. The simulations are performed on a biphasic system consisting of immiscible solvents (i.e., cyclohexane and water). We solvate a carbon nanoparticle into the cyclohexane layer and use a pull force to drive the nanoparticle into water, passing over the interface. Next, we accumulate a series of umbrella sampling simulations along the path of the nanoparticle and compute the solvation free energy with respect to the two solvents. We apply the method on three carbon nanoparticles (i.e., a carbon nanocone, a nanotube, and a graphene nanosheet). In addition, we record the water-accessible surface area of the nanoparticles during the umbrella simulations. Although we detect complete wetting of the external surface of the nanoparticles, the internal surface of the nanotube becomes partially wet, whereas that of the nanocone remains dry. This is due to the nanoconfinement of the particular nanoparticles, which shields the hydrophobic interactions encountered inside the pores. We show that cyclohexane molecules remain attached on the concave surface of the nanotube or the nanocone without being disturbed by the water molecules entering the cavity.

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Section: Introductionmentioning

confidence: 99%

Umbrella Sampling Simulations of Carbon Nanoparticles Crossing Immiscible Solvents

Gotzias

2022

Molecules

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Graphene Exfoliation in Binary NMP/Water Mixtures by Molecular Dynamics Simulations

Gotzias,

Lazarou

2024

ChemPlusChem

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We investigate the molecular mechanism underlying the liquid‐phase exfoliation of graphene in aqueous/N‐methyl‐2‐pyrrolidone (NMP) solvent mixtures and calculate the associated free energies, considering different NMP concentrations and exfoliation temperatures. We employ steered molecular dynamics to establish a path for the exfoliation of a graphene sheet from graphite within each solvent environment. Then, we conduct umbrella sampling simulations throughout the created paths to compute the potential of mean force (PMF) of the graphene sheet. As the nanosheet disperses into the liquid, it becomes fully covered by a solvent monolayer. We analyze the composition of the monolayer by measuring the contacts of either NMP or water molecules with the carbon surface. The carbon surface exhibits a preference for adsorbing NMP over water. The NMP molecules form a hydrophobic compact monolayer structure, effectively protecting the carbon interface from unfavorable interactions with water. The creation of the hydrophobic monolayer is a key factor in the exfoliation process, as it effectively inhibits the restacking of exfoliated nanosheets. An adequate level of graphene solubility is achieved through the addition of 20% to 30% water to NMP. This finding holds significant importance for improving efficiency and reducing dependence on organic solvents in the industrial manufacturing of graphene.

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Water to cyclohexane transfer free energy calculations for a carbon nanotube

Gotzias¹

2022

Carbon Trends

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On the Consistency of the Exfoliation Free Energy of Graphenes by Molecular Simulations

Cited by 4 publications

References 55 publications

Umbrella Sampling Simulations of Carbon Nanoparticles Crossing Immiscible Solvents

Umbrella Sampling Simulations of Carbon Nanoparticles Crossing Immiscible Solvents

Graphene Exfoliation in Binary NMP/Water Mixtures by Molecular Dynamics Simulations

Water to cyclohexane transfer free energy calculations for a carbon nanotube

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