Sulfonyl <scp>PIM</scp>‐1: A diverse separation membrane with dilation resistance

Anstine, Dylan M.; Mendez, Nicholas F.; Colina, Coray M.

doi:10.1002/aic.17006

Cited by 5 publications

(5 citation statements)

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“…Iterative-pressure MD simulations have been utilized to study CO 2 -induced hysteresis in polyimides for pressures upward of 60 bar . In addition to molecular dynamics methods, the combined Monte Carlo/molecular dynamics (MCMD) approach has been used to incorporate framework restructuring in response to species uptake for PIM-1 among other polymeric materials. ,,,,, …”

Section: Resultsmentioning

confidence: 99%

“…55 In addition to molecular dynamics methods, the combined Monte Carlo/molecular dynamics (MCMD) approach has been used to incorporate framework restructuring in response to species uptake for PIM-1 among other polymeric materials. 35,38,39,44,56,57 3.1. Sensitivity Analysis and Validation.…”

Section: Resultsmentioning

confidence: 99%

“…To account for the adsorbate-induced framework rearrangement that is characteristic of polymeric adsorbents at elevated loading conditions, adsorption simulations were also performed using a combined MCMD approach . This method has been previously applied for studying sorption-induced rearrangement in polyimides, , vinyl polymers, , ionic liquids, and cellulose-based materials as well as PIMs. ,, Accounting for structural rearrangement is essential for evaluating the adsorption performance of PIM-1 under the swelling/plasticization conditions encountered at the relatively high loadings studied. Adsorption-relaxation simulations are carried out in multiple iterations where GCMC simulations are used to predict adsorbate loading and MD simulations in the isothermal–isobaric ensemble are utilized to account for system restructuring.…”

Section: Methodsmentioning

confidence: 99%

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Temperature Effects in Flexible Adsorption Processes for Amorphous Microporous Polymers

2022

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A collection of atomistic molecular simulations is reported that illustrate the impact of adsorption temperature on species uptake and adsorbate-induced structural rearrangement for amorphous polymers of intrinsic microporosity. Temperature-sensitive structural rearrangement is evaluated by contrasting two methods: standard grand canonical Monte Carlo simulations using a rigid framework approximation and a combined Monte Carlo/molecular dynamics approach that fully incorporates framework flexibility. We report single-component gas phase adsorption isotherms for CH4, C2H4, C2H6, C3H6, C3H8, and CO2 across a temperature range of 250–400 K for models of an archetypal polymer of intrinsic microporosity, PIM-1. A quadratic model is presented that captures two main mechanisms of temperature-dependent adsorption-induced deformation of PIM-1 up to a relative swelling of 1.15: thermal expansion and an increased propensity to swell as a function of species uptake. Two case studies are reported that highlight the critical role of operating temperature in industrial storage and separation applications. The first study focuses on methane storage and delivery applications using a pressure–temperature swing adsorption application (PTSA). We demonstrate that larger working capacities are accompanied by increased volumetric strain between adsorption–desorption steps. The second case study considers PIM-1 as an adsorbent to separate an exemplar ternary syngas mixture at operating temperatures ranging 300–550 K. A temperature threshold of ∼400 K is identified, beyond which adsorption-induced PIM-1 swelling is negligible and the solubility selectivity-loading curve transitions to exhibiting a nearly linear relationship.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Temperature Effects in Flexible Adsorption Processes for Amorphous Microporous Polymers

2022

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“…Various methods have been developed to account for framework flexibility in modeling adsorption in porous materials. For frameworks that undergo structural changes due to breathing and swelling upon adsorption, conventional MC and molecular dynamics (MD) techniques may be combined in a hybrid scheme − or employed in a sequential manner. − Ghoufi and Maurin studied the adsorption of CO 2 in MIL-53(Cr) combining anisotropic isothermal/isobaric MD and GCMC methods in a hybrid manner to create an osmotic Monte Carlo (HOMC) scheme within the μ N σ T ensemble, where σ is the stress. The MD moves were integrated within the Markov chain to allow changes in the volume and shape of the framework.…”

Section: Introductionmentioning

confidence: 99%

“…Anstine et al studied adsorption of fluids in polymers of intrinsic microscopy (PIM) using the sorption–relaxation approach . This method was developed to investigate sorption-induced polymer rearrangements in PIMs, − a process similar to MOFs with Δ V ≠ 0. They used GCMC moves to predict the adsorbate loading at a fixed polymer configuration, followed by isothermal–isobaric MD simulations to relax the polymer, repeating the process sequentially.…”

Section: Introductionmentioning

confidence: 99%

Impact of Loading-Dependent Intrinsic Framework Flexibility on Adsorption in UiO-66

Shukla

Johnson

2022

J. Phys. Chem. C

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The vast majority of molecular simulations of adsorption in porous materials make use of the assumption that the framework of the porous material may be held rigid without significantly impacting the accuracy of the computed adsorption isotherm. One reason for this approximation is that explicit inclusion of framework flexibility in adsorption simulations dramatically increases the computational cost of the simulation. Approximate methods for including framework flexibility have been developed that are computationally efficient and have been applied to adsorption of gases in metal–organic frameworks (MOFs) by generating an ensemble of snapshots from a molecular dynamics calculation of an empty MOF and employing these snapshots to generate an isotherm averaged over all the snapshots, holding each snapshot rigid during the adsorption calculation. This method assumes that the adsorbate has negligible impact on the dynamic configurations of the MOF. We demonstrate an efficient method for including adsorbate-induced changes to the MOF framework and show that this assumption is not always valid. Specifically, for acetone and isopropyl alcohol adsorbed in UiO-66, the saturation loading and degree of hydrogen bonding with the framework significantly increased through the inclusion of adsorbate-induced framework flexibility. We show that adsorption simulations that include adsorbate-induced flexibility match the experimental data for these systems much better than simulations using either the rigid approximation or including the framework flexibility of the empty MOF. We expect that adsorbate-induced flexibility may be important for adsorption in many similar systems.

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