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Intercambio de capa sintonizable en marcos orgánicos covalentes bidimensionales desencadenados por la absorción de
Chengjun Kang1, Zhaoqiang Zhang1, Adam K Usadi2
1Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore 117585, Singapore.
Journal of the American Chemical Society
|October 31, 2022
Resumen
Los marcos orgánicos covalentes bidimensionales (2D COF) presentan una histeresis inesperada en la adsorción de CO2 debido al desplazamiento entre capas. Este descubrimiento revela que los COF 2D pueden comportarse como materiales "blandos", abriendo nuevas vías para las tecnologías de almacenamiento y separación de gases.
Área de la Ciencia:
- Ciencias de los materiales
- Química
- Nanotecnología
Sus antecedentes:
- Los marcos orgánicos covalentes bidimensionales (2D COF) se consideran típicamente materiales porosos rígidos.
- Sus isotermas de sorción de gas son generalmente suaves y reversibles.
Objetivo del estudio:
- Para investigar un paso de histeresis inusual observado en la isoterma de adsorción de CO2 de un COF 2D, TAPB-OMeTA.
- Comprender la dinámica estructural de los COF 2D durante la adsorción de gases.
Principales métodos:
- Mediciones de difracción de rayos X en polvo in situ (PXRD).
- Modelado computacional y refinamiento Pawley.
- Cálculos de la teoría funcional de la densidad (DFT).
- La polimerización por transferencia radical de átomos iniciada por la superficie (SI-ATRP) para la funcionalización.
Principales resultados:
- TAPB-OMeTA exhibe una etapa de histeresis en su isoterma de adsorción de CO2, atribuida al desplazamiento entre capas.
- Se forma una estructura de apilamiento cuasi-AA durante la adsorción de CO2 debido a la debilitada atracción y repulsión entre capas de los grupos metoxicos.
- La funcionalización con oligómeros de poli (N-isopropilacrilamida) indujo un segundo desplazamiento entre capas y dos etapas de adsorción, lo que demuestra la afinidad.
- Los cálculos de DFT confirmaron la preferencia energética por la estructura de apilamiento cuasi-AA bajo una atmósfera de CO2.
Conclusiones:
- Los COF 2D pueden exhibir un comportamiento poroso "blando" cuando interactúan con los gases, desafiando la visión tradicional de su rigidez.
- El desplazamiento entre capas, influenciado por las interacciones de los gases y la repulsión del grupo funcional, es un mecanismo clave para este comportamiento.
- La capacidad de ajuste del desplazamiento entre capas ofrece nuevas posibilidades para el diseño de COF 2D para aplicaciones avanzadas de almacenamiento y separación de gases.
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