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In Silico Determination of Gas Permeabilities by Non-Equilibrium Molecular Dynamics: CO2 and He through PIM-1.

Frentrup H, Hart KE, Colina CM, Müller EA - Membranes (Basel) (2015)

Bottom Line: We study the permeation dynamics of helium and carbon dioxide through an atomistically detailed model of a polymer of intrinsic microporosity, PIM-1, via non-equilibrium molecular dynamics (NEMD) simulations.This work presents the first explicit molecular modeling of gas permeation through a high free-volume polymer sample, and it demonstrates how permeability and solubility can be obtained coherently from a single simulation.Solubilities in particular can be obtained to a very high degree of confidence and within experimental inaccuracies.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK. hendrik.frentrup10@imperial.ac.uk.

ABSTRACT
We study the permeation dynamics of helium and carbon dioxide through an atomistically detailed model of a polymer of intrinsic microporosity, PIM-1, via non-equilibrium molecular dynamics (NEMD) simulations. This work presents the first explicit molecular modeling of gas permeation through a high free-volume polymer sample, and it demonstrates how permeability and solubility can be obtained coherently from a single simulation. Solubilities in particular can be obtained to a very high degree of confidence and within experimental inaccuracies. Furthermore, the simulations make it possible to obtain very specific information on the diffusion dynamics of penetrant molecules and yield detailed maps of gas occupancy, which are akin to a digital tomographic scan of the polymer network. In addition to determining permeability and solubility directly from NEMD simulations, the results shed light on the permeation mechanism of the penetrant gases, suggesting that the relative openness of the microporous topology promotes the anomalous diffusion of penetrant gases, which entails a deviation from the pore hopping mechanism usually observed in gas diffusion in polymers.

No MeSH data available.


Related in: MedlinePlus

(Top) Snapshot of an instantaneous configuration of the simulation cell. Periodic boundary conditions are applied in all directions and an external force applied to the fluid molecules in the left boundary. Carbon dioxide molecules are depicted by black and red, while a stick representation of a slab of PIM-1 is shown in yellow. (Bottom) Average velocity profile in the direction of transport (red) and the fluid density profile (blue) across the simulation cell. Density within the porous region is referred to the total volume, including the polymer.
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f2-membranes-05-00099: (Top) Snapshot of an instantaneous configuration of the simulation cell. Periodic boundary conditions are applied in all directions and an external force applied to the fluid molecules in the left boundary. Carbon dioxide molecules are depicted by black and red, while a stick representation of a slab of PIM-1 is shown in yellow. (Bottom) Average velocity profile in the direction of transport (red) and the fluid density profile (blue) across the simulation cell. Density within the porous region is referred to the total volume, including the polymer.

Mentions: The final polymerized structure of the thin-slice PIM-1 (polymer of intrinsic microporosity) simulation box, PIM-1 (2D). The polymer is polymerized and periodic in the x and y dimensions, with the z dimension being capped by fluid-transparent rigid walls. The polymer is illustrated in unwrapped coordinates; however, periodic boundary conditions were used, with the wrapped coordinates sample shown in Figure 2.


In Silico Determination of Gas Permeabilities by Non-Equilibrium Molecular Dynamics: CO2 and He through PIM-1.

Frentrup H, Hart KE, Colina CM, Müller EA - Membranes (Basel) (2015)

(Top) Snapshot of an instantaneous configuration of the simulation cell. Periodic boundary conditions are applied in all directions and an external force applied to the fluid molecules in the left boundary. Carbon dioxide molecules are depicted by black and red, while a stick representation of a slab of PIM-1 is shown in yellow. (Bottom) Average velocity profile in the direction of transport (red) and the fluid density profile (blue) across the simulation cell. Density within the porous region is referred to the total volume, including the polymer.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4384093&req=5

f2-membranes-05-00099: (Top) Snapshot of an instantaneous configuration of the simulation cell. Periodic boundary conditions are applied in all directions and an external force applied to the fluid molecules in the left boundary. Carbon dioxide molecules are depicted by black and red, while a stick representation of a slab of PIM-1 is shown in yellow. (Bottom) Average velocity profile in the direction of transport (red) and the fluid density profile (blue) across the simulation cell. Density within the porous region is referred to the total volume, including the polymer.
Mentions: The final polymerized structure of the thin-slice PIM-1 (polymer of intrinsic microporosity) simulation box, PIM-1 (2D). The polymer is polymerized and periodic in the x and y dimensions, with the z dimension being capped by fluid-transparent rigid walls. The polymer is illustrated in unwrapped coordinates; however, periodic boundary conditions were used, with the wrapped coordinates sample shown in Figure 2.

Bottom Line: We study the permeation dynamics of helium and carbon dioxide through an atomistically detailed model of a polymer of intrinsic microporosity, PIM-1, via non-equilibrium molecular dynamics (NEMD) simulations.This work presents the first explicit molecular modeling of gas permeation through a high free-volume polymer sample, and it demonstrates how permeability and solubility can be obtained coherently from a single simulation.Solubilities in particular can be obtained to a very high degree of confidence and within experimental inaccuracies.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK. hendrik.frentrup10@imperial.ac.uk.

ABSTRACT
We study the permeation dynamics of helium and carbon dioxide through an atomistically detailed model of a polymer of intrinsic microporosity, PIM-1, via non-equilibrium molecular dynamics (NEMD) simulations. This work presents the first explicit molecular modeling of gas permeation through a high free-volume polymer sample, and it demonstrates how permeability and solubility can be obtained coherently from a single simulation. Solubilities in particular can be obtained to a very high degree of confidence and within experimental inaccuracies. Furthermore, the simulations make it possible to obtain very specific information on the diffusion dynamics of penetrant molecules and yield detailed maps of gas occupancy, which are akin to a digital tomographic scan of the polymer network. In addition to determining permeability and solubility directly from NEMD simulations, the results shed light on the permeation mechanism of the penetrant gases, suggesting that the relative openness of the microporous topology promotes the anomalous diffusion of penetrant gases, which entails a deviation from the pore hopping mechanism usually observed in gas diffusion in polymers.

No MeSH data available.


Related in: MedlinePlus