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Showing posts with label 2014. Show all posts
Showing posts with label 2014. Show all posts
Prof. Cafer, Jeongin, and Jeehye participated in NANO-7 held in Niagara Fall, Canada!
Exceptional organic solvent uptake by disulfide-linked polymeric networks
Disulfide-linked covalent organic polymers (COPs) were prepared through catalyst-free oxidative coupling polymerization. Owing to the excellent swelling behavior, low cost, and efficient synthesis, these materials can be promising materials for removal of organics in concentrated streams. COPs show 1,4-dioxane uptake up to 1.8 g g−1.
Nanoporous covalent organic polymers incorporating Tröger’s base functionalities for enhanced CO2 capture
J. Byun, S. H. Je, H. A. Patel, A. Coskun,* C. T. Yavuz*
J. Mater. Chem. A, 2, 12507-12512, 2014. [DOI] [pdf] [WoS]
The CO2 uptake capacity and CO2/N2 selectivity of Tröger’s base–bridged nanoporous covalent organic polymers (TB-COPs) were investigated. TB-COPs were synthesized by reacting amine terminals of tetrahedral monomers - namely, tetraanilyladamantane and tetraanilylmethane - with dimethoxymethane in a one–pot reaction under relatively mild conditions. Interestingly, these two tetrahedral monomers formed nanoporous polymers with substantially different surface areas. While the trögerization of tetraanilyladamantane monomer (TB-COP-1) exhibit high surface area of 1340 m2 g-1, that of tetraanilylmethane monomer (TB-COP-2) is found to be only 0.094 m2 g-1. This unusual phenomenon can be explained by the proximity of amino moieties to each other within the monomeric unit. Shorter distance between the amino groups enables intramolecular cyclization along with the intermolecular one, thus resulting in much lower porosity. TB-COP-1 exhibits significant CO2 uptakes up to 5.19 and 3.16 mmol g-1 at 273 and 298K under ambient pressure, and CO2/N2 selectivities of 79.2 and 68.9 at 273 and 298K at 1 bar for the gas mixture of CO2:N2 in the ratio of 0.15:0.85. It is noteworthy that TB-COP-1 showed remarkable selectivity retention with rising temperature from 273 to 298 K.
J. Mater. Chem. A, 2, 12507-12512, 2014. [DOI] [pdf] [WoS]
The CO2 uptake capacity and CO2/N2 selectivity of Tröger’s base–bridged nanoporous covalent organic polymers (TB-COPs) were investigated. TB-COPs were synthesized by reacting amine terminals of tetrahedral monomers - namely, tetraanilyladamantane and tetraanilylmethane - with dimethoxymethane in a one–pot reaction under relatively mild conditions. Interestingly, these two tetrahedral monomers formed nanoporous polymers with substantially different surface areas. While the trögerization of tetraanilyladamantane monomer (TB-COP-1) exhibit high surface area of 1340 m2 g-1, that of tetraanilylmethane monomer (TB-COP-2) is found to be only 0.094 m2 g-1. This unusual phenomenon can be explained by the proximity of amino moieties to each other within the monomeric unit. Shorter distance between the amino groups enables intramolecular cyclization along with the intermolecular one, thus resulting in much lower porosity. TB-COP-1 exhibits significant CO2 uptakes up to 5.19 and 3.16 mmol g-1 at 273 and 298K under ambient pressure, and CO2/N2 selectivities of 79.2 and 68.9 at 273 and 298K at 1 bar for the gas mixture of CO2:N2 in the ratio of 0.15:0.85. It is noteworthy that TB-COP-1 showed remarkable selectivity retention with rising temperature from 273 to 298 K.
Directing the Structural Features of N2-Phobic Nanoporous Covalent Organic Polymers for CO2 Capture and Separation
H. A. Patel, S. H. Je, J. Park, Y. Jung, A. Coskun*, C. T. Yavuz*
Chem. Eur. J., 20, 772-780, (2014). [DOI] [pdf] [WOS]
Chem. Eur. J., 20, 772-780, (2014). [DOI] [pdf] [WOS]
A family of azo-bridged covalent organic polymers (azo-COPs) was synthesized through a catalyst-free direct coupling of aromatic nitro and amine compounds under basic conditions. The azo-COPs formed 3D nanoporous networks and exhibited surface areas up to 729.6 m2 g−1, with a CO2-uptake capacity as high as 2.55 mmol g−1 at 273 K and 1 bar. Azo-COPs showed remarkable CO2/N2 selectivities (95.6–165.2) at 298 K and 1 bar. Unlike any other porous material, CO2/N2 selectivities of azo-COPs increase with rising temperature. It was found that azo-COPs show less than expected affinity towards N2 gas, thus making the framework “N2-phobic”, in relative terms. Our theoretical simulations indicate that the origin of this unusual behavior is associated with the larger entropic loss of N2 gas molecules upon their interaction with azo-groups. The effect of fused aromatic rings on the CO2/N2 selectivity in azo-COPs is also demonstrated. Increasing the π-surface area resulted in an increase in the CO2-philic nature of the framework, thus allowing us to reach a CO2/N2 selectivity value of 307.7 at 323 K and 1 bar, which is the highest value reported to date. Hence, it is possible to combine the concepts of “CO2-philicity” and “N2-phobicity” for efficient CO2 capture and separation. Isosteric heats of CO2 adsorption for azo-COPs range from 24.8–32.1 kJ mol−1 at ambient pressure. Azo-COPs are stable up to 350 °C in air and boiling water for a week. A promising cis/trans isomerization of azo-COPs for switchable porosity is also demonstrated, making way for a gated CO2 uptake.
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