Highly Permeable Oligo(ethylene oxide)‐co‐poly(dimethylsiloxane) Membranes for Carbon Dioxide Separation

Abstract

A series of cross‐linked, freestanding oligo(ethylene oxide)‐co‐(polydimethylsiloxane‐norbornene) membranes with varied composition is synthesized via in situ ring‐opening metathesis polymerization. These membranes show remarkably high CO2 permeabilities (3400 Barrer) and their separation performance approaches the Robeson upper bound. The excellent permeability of these copolymer membranes provides great potential for real‐world applications where enormous volumes of gases must be separated. The gas transport properties of these films are found to be directly proportional to oligo(ethylene oxide) content incorporation, which stems from the increased solubility selectivity change within the copolymer matrix. This work provides a systematic study of how gas separation performance in rubbery membranes can be enhanced by tuning the CO2‐philicity of their constituent monomeric subunits.

Highly Polar but Amorphous Polymers with Robust Membrane CO2/N2 Separation Performance

“…To achieve high CO 2 /N 2 selectivity, a membrane must exhibit favorable interaction with CO 2 to enhance the CO 2 /gas solubility selectivity. 16,17 Poly(ethylene oxide) (PEO)-containing materials have been the leading membrane materials for CO 2 /N 2 separation with a balanced high CO 2 permeability and CO 2 /N 2 selectivity, [17][18][19] such as block copolymers with PEO blocks (Pebax and Polyactive), [20][21][22][23] crosslinked PEO, [24][25][26][27][28][29][30] and PEO-based nanocomposites. 19,31,32 The ethylene oxide repeating units exhibit strong affinity towards CO 2 but not N 2 (which leads to high CO 2 solubility and CO 2 /N 2 solubility selectivity) while retaining polymer chain flexibility and thus high CO 2 diffusivity.…”

PEG/PPG-PDMS-Adamantane-Based Crosslinked Terpolymer Using the ROMP Technique to Prepare a Highly Permeable and CO2-Selective Polymer Membrane

“…The C=O peaks, which corresponded to imides, were observed for all three membranes, both at 1768 and 1700 cm −1 . Further, the common peaks at 1456 cm −1 were attributed to the deformation of the –CH 2 contained in PEG/PPG [ 30 ]. In addition, the broad peaks observed at 1184–972 cm −1 were attributed to the large number of C–O–C bonds and Si–O–Si bonds repeated in the PEG/PPG and PDMS structures.…”

“…Subsequently, the solution was carefully poured into the petri dish (made of polypropylene) and dried overnight. To terminate the reaction, dichloromethane containing ethyl vinyl ether was dropped onto the membrane [ 30 , 31 ]. The film was carefully peeled off and dried in a 40 °C vacuum oven for 2 days.…”

“…To compare the gas separation performance of the developed polymer membranes, the data points were plotted on a Robeson plot, and the data are compared with that for typical rubbery polymer-based membranes [11,13,21,26,30,31,[41][42][43][44][45] (Figure 9). We found that our x(PEG/PPG:PDMS:Ad) membranes had both higher permeability and CO 2 /N 2 selectivity than most PEG-based membranes, and a hybrid crosslinking membrane of PEG and silane, surpassing the 2008 Robeson upper bound for CO 2 /N 2 (Figure 9a).…”

Representation of Molecular Structures with Persistent Homology Leads to the Discovery of Molecular Groups with Enhanced CO2 Binding

“…Unlike solvents, where chemisorption involves a reaction with binding strengths exceeding 20 kcal/mol through the creation of chemical bonds between CO 2 and solvent, membranes utilize much weaker noncovalent interactions. Different types of materials have been suggested for the fabrication of permeable membranes including amorphous, non-porous polymeric membranes, [3][4][5][6][7][8][9] or crystalline materials with permanent porosity such as metal-organic frameworks (MOFs) [10][11][12] or zeolites. [13][14][15][16][17] The understanding of how the atomistic structure of materials affects the gas selectivies is a crucial process for the development of more efficient carbon capture technologies.…”