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On the Order and Orientation in Liquid Crystalline Polymer Membranes for Gas Separation

[Image: see text] To prevent greenhouse emissions into the atmosphere, separations like CO(2)/CH(4) and CO(2)/N(2) from natural gas, biogas, and flue gasses are crucial. Polymer membranes gained a key role in gas separations over the past decades, but these polymers are often not organized at a mole...

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Autores principales: Kloos, Joey, Jansen, Nico, Houben, Menno, Casimiro, Anna, Lub, Johan, Borneman, Zandrie, Schenning, Albert P.H.J., Nijmeijer, Kitty
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2021
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8587323/
https://www.ncbi.nlm.nih.gov/pubmed/34776611
http://dx.doi.org/10.1021/acs.chemmater.1c02526
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author Kloos, Joey
Jansen, Nico
Houben, Menno
Casimiro, Anna
Lub, Johan
Borneman, Zandrie
Schenning, Albert P.H.J.
Nijmeijer, Kitty
author_facet Kloos, Joey
Jansen, Nico
Houben, Menno
Casimiro, Anna
Lub, Johan
Borneman, Zandrie
Schenning, Albert P.H.J.
Nijmeijer, Kitty
author_sort Kloos, Joey
collection PubMed
description [Image: see text] To prevent greenhouse emissions into the atmosphere, separations like CO(2)/CH(4) and CO(2)/N(2) from natural gas, biogas, and flue gasses are crucial. Polymer membranes gained a key role in gas separations over the past decades, but these polymers are often not organized at a molecular level, which results in a trade-off between permeability and selectivity. In this work, the effect of molecular order and orientation in liquid crystals (LCs) polymer membranes for gas permeation is demonstrated. Using the self-assembly of polymerizable LCs to prepare membranes ensures control over the supramolecular organization and alignment of the building blocks at a molecular level. Robust freestanding LC membranes were fabricated that have various, distinct morphologies (isotropic, nematic cybotactic, and smectic C) and alignment (planar and homeotropic), while using the same chemical composition. Single gas permeation data show that the permeability decreases with increasing molecular order while the ideal gas selectivity of He and CO(2) over N(2) increases tremendously (36-fold for He/N(2) and 21-fold for CO(2)/N(2)) when going from randomly ordered to the highly ordered smectic C morphology. The calculated diffusion coefficients showed a 10-fold decrease when going from randomly ordered membranes to ordered smectic C membranes. It is proposed that with increasing molecular order, the free volume elements in the membrane become smaller, which hinders gasses with larger kinetic diameters (Ar, N(2)) more than gasses with smaller kinetic diameters (He, CO(2)), inducing selectivity. Comparison of gas sorption and permeation performances of planar and homeotropic aligned smectic C membranes shows the effect of molecular orientation by a 3-fold decrease of the diffusion coefficient of homeotropic aligned smectic C membranes resulting in a diminished gas permeation and increased ideal gas selectivities. These results strongly highlight the importance of molecular order and orientation in LC polymer membranes for gas separation.
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spelling pubmed-85873232021-11-12 On the Order and Orientation in Liquid Crystalline Polymer Membranes for Gas Separation Kloos, Joey Jansen, Nico Houben, Menno Casimiro, Anna Lub, Johan Borneman, Zandrie Schenning, Albert P.H.J. Nijmeijer, Kitty Chem Mater [Image: see text] To prevent greenhouse emissions into the atmosphere, separations like CO(2)/CH(4) and CO(2)/N(2) from natural gas, biogas, and flue gasses are crucial. Polymer membranes gained a key role in gas separations over the past decades, but these polymers are often not organized at a molecular level, which results in a trade-off between permeability and selectivity. In this work, the effect of molecular order and orientation in liquid crystals (LCs) polymer membranes for gas permeation is demonstrated. Using the self-assembly of polymerizable LCs to prepare membranes ensures control over the supramolecular organization and alignment of the building blocks at a molecular level. Robust freestanding LC membranes were fabricated that have various, distinct morphologies (isotropic, nematic cybotactic, and smectic C) and alignment (planar and homeotropic), while using the same chemical composition. Single gas permeation data show that the permeability decreases with increasing molecular order while the ideal gas selectivity of He and CO(2) over N(2) increases tremendously (36-fold for He/N(2) and 21-fold for CO(2)/N(2)) when going from randomly ordered to the highly ordered smectic C morphology. The calculated diffusion coefficients showed a 10-fold decrease when going from randomly ordered membranes to ordered smectic C membranes. It is proposed that with increasing molecular order, the free volume elements in the membrane become smaller, which hinders gasses with larger kinetic diameters (Ar, N(2)) more than gasses with smaller kinetic diameters (He, CO(2)), inducing selectivity. Comparison of gas sorption and permeation performances of planar and homeotropic aligned smectic C membranes shows the effect of molecular orientation by a 3-fold decrease of the diffusion coefficient of homeotropic aligned smectic C membranes resulting in a diminished gas permeation and increased ideal gas selectivities. These results strongly highlight the importance of molecular order and orientation in LC polymer membranes for gas separation. American Chemical Society 2021-10-25 2021-11-09 /pmc/articles/PMC8587323/ /pubmed/34776611 http://dx.doi.org/10.1021/acs.chemmater.1c02526 Text en © 2021 The Authors. Published by American Chemical Society https://creativecommons.org/licenses/by-nc-nd/4.0/Permits non-commercial access and re-use, provided that author attribution and integrity are maintained; but does not permit creation of adaptations or other derivative works (https://creativecommons.org/licenses/by-nc-nd/4.0/).
spellingShingle Kloos, Joey
Jansen, Nico
Houben, Menno
Casimiro, Anna
Lub, Johan
Borneman, Zandrie
Schenning, Albert P.H.J.
Nijmeijer, Kitty
On the Order and Orientation in Liquid Crystalline Polymer Membranes for Gas Separation
title On the Order and Orientation in Liquid Crystalline Polymer Membranes for Gas Separation
title_full On the Order and Orientation in Liquid Crystalline Polymer Membranes for Gas Separation
title_fullStr On the Order and Orientation in Liquid Crystalline Polymer Membranes for Gas Separation
title_full_unstemmed On the Order and Orientation in Liquid Crystalline Polymer Membranes for Gas Separation
title_short On the Order and Orientation in Liquid Crystalline Polymer Membranes for Gas Separation
title_sort on the order and orientation in liquid crystalline polymer membranes for gas separation
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8587323/
https://www.ncbi.nlm.nih.gov/pubmed/34776611
http://dx.doi.org/10.1021/acs.chemmater.1c02526
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