Membranes For CO2 Capture Research Articles

CO2‐Responsive Copolymers for Membrane Applications, Synthesis, and Performance Evaluation

AbstractThe urgent need to mitigate climate change has spurred research into innovative carbon dioxide (CO2) capture materials. In this study, the design and synthesis of CO2‐responsive diblock copolymers, poly (N‐[3‐(dimethylamino)propyl]‐acrylamide)‐b‐poly(methyl methacrylate) (PDMAPAm‐b‐PMMA) are focused on via a two‐step reversible addition−fragmentation chain‐transfer (RAFT) polymerization as well as the application of the synthesized diblock copolymer as a membrane for CO2 capture. The resulting diblock copolymer possesses distinct blocks with varying properties. The poly (N‐[3‐(dimethylamino)propyl]‐acrylamide) (PDMAPAm) block provides CO2‐responsive behavior, while the poly(methyl methacrylate) (PMMA) block contributes to mechanical stability. The gas transport properties of the fabricated thin‐film composite membrane made of PDMAPAm‐b‐PMMA are measured. It is determined that the copolymer exhibits dual responsiveness towards CO2 and can be tailored for use in fabrication of membranes for direct air capture (DAC).

Low-cost, all-organic, hydrogen-bonded thin-film composite membranes for CO2 capture: Experiments and molecular dynamic simulations

Despite the excellent separation performance of organic-inorganic hybrid membranes, such as mixed-matrix membranes, their commercial application remains challenging due to difficulties in uniformly dispersing inorganic fillers and achieving good interfacial contact over large areas. In this paper, we present high-performance, thin-film composite (TFC) membranes made from low-cost, all-organic materials using a commercially attractive and straightforward process for CO2 capture. The TFC membranes were prepared on a porous polysulfone support using 2,4,6-triaminopyrimidine (TAP) dispersed in comb-shaped polymerized poly(oxyethylene methacrylate) (PPOEM), synthesized through a free radical polymerization process. The organic filler TAP functioned as a hydrogen bond inducer, controlling the free volume and reducing gas diffusivity, thereby enhancing CO2 selectivity over larger gases such as N2 and CH4. Incorporating 2 wt% TAP significantly improved separation performance by primarily reducing N2 and CH4 permeances, achieving a CO2 permeance of 1140 GPU, with CO2/N2 and CO2/CH4 selectivities of 43.3 and 15.0, respectively. The achieved performance significantly surpassed that of Pebax-based membranes and successfully met the target criteria for post-combustion CO2 capture. Variations in free volume, molecule aggregation, hydrogen bonding, and interaction energies between gases and membranes were thoroughly investigated via molecular dynamic (MD) simulations. This high-performance TFC membrane, created through simple and facile methods using entirely organic materials, achieves commercial standards for post-combustion CO2 capture.

Accelerated CO2 preferential permeation using graphene oxide confined ionic liquid membranes for CO2/H2 separation

Due to the enhanced mass transfer process of nanochannels and the high affinity of ionic liquids (ILs) for carbon dioxide (CO2), the membranes combined with 2D nanosheets and ILs have attracted significant attention in carbon capture, utilization, and storage (CCUS). However, regulating the structure of IL to enhance the separation performance of CO2 remains a big challenge. Herein, we selected different imidazolium-based ILs and proposed a simple strategy to prepare nano-confined IL membranes by intercalating ILs into graphene oxide (GO). These membranes are subsequently used to remove CO2 from industrial syngases, where they display an abnormal CO2 preferential permeation process relative to the smaller H2 molecule. Meanwhile, CO2 permeation decreases gradually with the increase of alkyl chain length, whereas CO2/H2 selectivity shows a tendency to first increase and then decrease. Interestingly, all GO-confined IL membranes surpass the Robeson upper bound, achieving peak CO2 permeance of 13.85 GPU and CO2/H2 selectivity of 13.58, respectively. Further characterization of the interlayer spacing and density functional theory (DFT) calculations reveal that the high CO2/H2 separation performance mainly arises from the fact that nano-confined ILs can block the transit of H2 through the dense packing structure, simultaneously enhancing CO2 solubility and permeability through the membrane. These quantitative insights into the nanoconfined IL membrane not only deepen the scientific understanding of the abnormal transfer process within the nanochannel but also propose novel methodologies for preparing high-performance CO2 capture membranes.

Molecular dynamics simulation of the relationship between hydration and water mobilities around piperazine-immobilized polyvinyl alcohol membranes for CO2 capture

Molecular dynamics simulation of the relationship between hydration and water mobilities around piperazine-immobilized polyvinyl alcohol membranes for CO2 capture

Polymer-functionalized metal-organic framework nanosheet membranes for efficient CO2 capture

Two-dimensional metal-organic frameworks (2DMOFs) have emerged as highly appealing candidates as advanced separation membrane materials. However, constructing 2DMOF membranes with appropriate channel sizes to separate CO2 from N2 remains a great challenge. Here, we propose an in-situ crystallization approach to synthesize CO2-philic-polymer functionalized Zr-based MOF nanosheets, enabling the fabrication of efficient CO2 capture membranes. The in-situ MOF crystallization with polyethylenimine (PEI) polymers leads to a uniform distribution of amines, resulting in the formation of PEI-NUS hybrid nanosheet characterized by both high porosity and strong affinity to CO2. These nanosheets are assembled into ultrathin lamellar membranes with thicknesses ranging from 40 to 120 nm. The amines of PEI polymers significantly facilitate the CO2 transfer as reaction carriers, resulting in a substantially improved CO2/N2 separation performance with a CO2 permeance of 410 GPU and a CO2/N2 selectivity of 90, which are among the best for MOF membranes in CO2 separation. This in-situ functionalization strategy paves the way for the fabrication of ultrathin 2D membranes for various separations.

Sub-nano porous graphene-based membranes enabled by in-situ-grown ZIF-8 for enhanced CO2 capture

Graphene oxide (GO) membranes hold promise for selective CO2 adsorption over N2 due to their carboxyl groups, making them attractive for flue gas CO2 capture. However, challenges such as limited carboxyl content, flexible nanosheets, and dense layer stacking hinder their N2/CO2 gas selectivity, pressure resistance, and permeability. In this study, we introduce a specific sub-nanometer framework structure within GO membranes by in-situ growing ZIF-8 nanocrystals. This novel approach, achieved through simultaneous infiltration of zinc nitrate and 2-methylimidazole precursors on both sides of the membrane, enhances CO2 capture and pressure resistance capabilities of resulting ZIF-8@GO composite membranes. Additionally, the incorporation of carboxylated wrinkled graphene (WG) and ethylenediamine (EDA) cross-linking agent molecules improves CO2 capture capability and introduces reinforced porous structures to enhance permeability. Experimental results demonstrate remarkable permeability, selectivity, and pressure resistance of the prepared ZIF-8@EDA-GO/WG composite membranes. Under a gas pressure of 0.2 MPa, permeability reaches 1850 GPU, with theoretical selectivity for N2/CO2 single gas and separation factors for mixed gases of 18.3 and 32.3, respectively, surpassing conventional GO membranes (3 GPU, 1.1, and 1.2). Even under elevated air pressure conditions (1.2 MPa), the composite membranes maintain a theoretical selectivity of 13.4. Our CO2 capture membrane design strategy not only advances the development of functional membranes but also contributes to mitigating CO2 emissions from flue gas, thereby combating global warming.

Intermediate layer free PVDF evolved CMS on ceramic hollow fiber membrane for CO2 capture

The use of carbonized polymers has ushered in a new class of materials with profound implications for the gas separation industry. This study explored the transformation of polyvinylidene fluoride (PVDF) into microporous carbon structures coated onto ceramic substrates, enabling in situ growth of carbon molecular sieve (CMS) materials over hollow fibers. This material featured more robust CMS membranes than alumina and demonstrated exceptional capability in vital gas separations, particularly for CO2/CH4. This novel approach increased the selectivity for gases and exhibited remarkable aging resilience, so the material is a compelling candidate for high-performance gas separations. Furthermore, after 31 days, the weathered carbon dioxide membrane exhibited a slight permeability drift from 234.88 barrers to 195.35 barrers, while the CO2/CH4 ratio increased from 24.21 to 57.14, surpassing the Robeson 2008 upper bound. The PVDF-derived supported hollow fiber carbon membranes provide a blueprint for designing membranes for carbon capture. With the high packing density of the hollow fiber membrane and improved mechanical strength of the supported carbon membrane, this approach overcame the high fabrication costs and brittleness of other carbon membranes. In addition, the entire process for preparation of the PVDF carbon films is easily scaled up and has great potential for future practical application.

Synergistic effect of combining UiO-66 nanoparticles and MXene nanosheets in Pebax mixed-matrix membranes for CO2 capture

The use of membrane-based gas separation has garnered significant interest owing to its cost-effectiveness, outstanding performance and positive environmental impact. The performance of gas separation membranes can be considerably enhanced by mixed-matrix membranes (MMMs), but poor interactions between additives and membrane matrix and the agglomeration of highly incorporated fillers in MMMs limit the benefits of overcoming tradeoff effect. Therefore, the regulation of the state of fillers in membrane matrix is a crucial indicator in the development of MMMs. In this study, MXene (Ti3C2Tx) nanosheets and UiO-66 nanoparticles were prepared and used as fillers, in combination with a Pepax-1657 matrix, to synthesize MMMs for CO2-gas separation. As-prepared MMMs were used for the separation; the large pores (0.5–0.6 nm) of UiO-66 served as a highway to enhance CO2 permeability, and MXene nanosheets were used as selective channels to achieve high selectivity via the terminal polar surface groups of MXene. The combination of UiO-66 and MXene not only enhanced the selectivity, but also increased the solubility and diffusivity via selective CO2 adsorption and the tortuous pathway provided by MXene nanosheets. As a result, adding MXene and UiO-66 to Pebax helped MMMs overcome the tradeoff effect. MMMs loaded with 10 wt% MXene/UiO-66 exhibited a CO2 permeability coefficient of 214.6 Barrer and an ideal CO2/N2 selectivity coefficient of 102. Dual filler-containing MMMs showed enhanced CO2 permeability coefficient and CO2/N2 selectivity in comparison to pristine Pebax and individual nanofiller-added membranes. In this study, the combination of 2D MXene and UiO-66 nanoparticles exerted a synergistic effect in improving the CO2 separation efficiency of MMMs. This research provides a novel route for fabricating high-performance MMMs in the separation of CO2.

Sulfonated Chitosan Gel Membrane with Confined Amine Carriers for Stable and Efficient Carbon Dioxide Capture.

Capturing carbon dioxide (CO2) from flue gases is a crucial step towards reducing CO2 emissions. Among the various carbon capture methods, facilitated transport membranes (FTMs) have emerged as a promising technology for CO2 capture owing to their high efficiency and low energy consumption in separating CO2. However, FTMs still face the challenge of losing mobile carriers due to weak interaction between the carriers and membrane matrix. Herein, we report a sulfonated chitosan (SCS) gel membrane with confined amine carriers for effective CO2 capture. In this structure, diethylenetriamine (DETA) as a CO2-mobile carrier is confined within the SCS gel membrane via electrostatic forces, which can react reversibly with CO2 and thus greatly facilitate its transport. The SCS ion gel membrane allows for the fast diffusion of amine carriers within it while blocking the diffusion of nonreactive gases, like N2. Thus, the prepared membrane exhibits exceptional CO2 separation capabilities when tested under simulated flue gas conditions with CO2 permeance of 1155 GPU and an ultra-high CO2/N2 selectivity of above 550. Moreover, the membrane retains a stable separation performance during the 170 h continuous test. The excellent CO2 separation performance demonstrates the high potential of gel membranes for CO2 capture from flue gas.

Manipulating the monomers supply of interfacial polymerization towards the ultrathin polyamide composite membrane for CO2 capture

Preparing polyamide (PA) composite membranes with high gas separation performance requires rational control for the interfacial polymerization (IP) process. In this study, the monomer supply of piperazine (PIP) and trimesoyl chloride (TMC) in the IP process was precisely manipulated to generate an ultrathin PA film on the polydimethylsiloxane (PDMS) gutter layer for CO2 separation. Concretely, the PIP supply was regulated from the homogeneous, slow, and excess mode to the inhomogeneous, fast, and small mode by constructing a sodium dodecyl sulfate (SDS) array at the phase interface; subsequently, the TMC supply was increased by elevating the TMC concentration. Therefore, the amine-to-acid chloride concentration ratio in the reaction zone was optimized and, as a consequence, the IP reaction rate was significantly increased. As a result, the thickness of the PA film was reduced from ∼92 nm to ∼37 nm through the optimization of SDS and TMC concentrations, and accordingly, the CO2 permeance was increased from 501 GPU to 1498 GPU under 0.1 MPa without sacrificing selectivity. Moreover, the membrane preparation efficiency was greatly improved with an IP reaction time of less than 30 s. The insights provided could promote the industrial application of interfacial polymerization in the scale-up preparation of high-performance CO2 separation membranes.

Green delamination of 2D LDH nanosheets incorporated in mixed matrix membrane for CO2 capture

Carbon capture is a critical issue due to worsening global warming. Mixed matrix membranes incorporating 2D fillers have been attractive since they exhibit superior separation performance. In this study, the synthesis of ALDH was adjusted by sodium dodecyl sulfate (SDS) intercalation and 3-aminopropyltrimethoxysilane (APTMS) surface functionalization. Owing to this modification, the ALDH was delaminated in Pebax solutions, leading to a green process for fabricating 2D ALDH nanosheets incorporated in mixed matrix membranes. Due to the increased filler-polymer interfacial area produced by the ALDH nanosheets, CO2 passed through the membrane more quickly, which endowed the membrane with efficient CO2 separation performance. The optimal performance was obtained by adding 50 % PEGDME and 4 % ALDH to Pebax-1657, and the CO2 permeability and CO2/N2 selectivity were 460 barrer and 63, respectively. No toxic solvent was used in the process, providing an environmentally friendly method for fabricating 2D ALDH MMMs for efficient CO2 capture.

Nanofluids and Nanocomposite Membranes for Enhanced CO2 Capture: A Comprehensive Review

Abstract The increasing concentration of greenhouse gasses in Earth's atmosphere is a critical concern, of which 75% of carbon dioxide (CO2) emissions are from the combustion of fossil fuels. This rapid increase in emissions led to irredeemable damages to ecosystems, such as climate change and acid rain. As a result, industries and academia have focused on developing innovative and cost-effective technologies for CO2 capture and storage (CCS). Physical/chemical absorption using amine and membrane-based technologies is generally used in CCS systems. However, the inherent technical and cost-effective limitations of these techniques directed their attention toward applying nanotechnologies for CCS systems. Here, the researchers have focused on infusing nanoparticles (NPs) into existing CCS technologies. The NPs could either be suspended in a base fluid to create nanofluids (NFs) or infused with membrane base materials to create nanocomposite membranes for enhanced carbon capture capabilities. This review paper investigates the manufacturing methods, characterization techniques, and various mechanisms to analyze the impact of nanoparticles-infused nanofluids and nanocomposite membranes for CO2 capture. Finally, the paper summarizes the factors associated with the two technologies and then outlines the drawbacks and benefits of incorporating NPs for CCS applications.

Nanocellulose‐Incorporated Composite Membranes of PEO‐Based Rubbery Polymers for Carbon Dioxide Capture

To achieve sustainable and energy‐efficient CO2 capture processes, it is imperative to develop membranes that possess both high CO2 permeability and selectivity. One promising approach involves integrating high‐aspect‐ratio nanoscale fillers into polymer matrices. The high‐aspect‐ratio fillers increase surface area and improve interactions between polymer chains and gas molecules passing through the membrane. This study focuses on the integration of cellulose nanocrystals (CNCs) with an impressive aspect ratio of around 12 into rubbery polymers containing polyethylene oxide (PEO), namely PEBAX MH 1657 (poly[ether‐block‐amide] [PEBA]) and polyurethane (PU), to fabricate mixed‐matrix membranes (MMMs). By exploiting the interfacial interactions between the polymer matrix and CNC nanofillers, combined with the surface functionalities of CNC nanofillers, the rapid and selective CO2 transport is facilitated, even at low filler concentrations. This unique feature enables the development of thin‐film composites (TFCs) with a selective layer around 1 μm. Notably, even at a filling ratio as low as 1 weight percent, the resulting membranes exhibit remarkable CO2 permeability (>90 Barrer) and CO2/N2 selectivity (>70). These findings highlight the potential of integrating CNCs into rubbery polymers as a promising strategy for the design and fabrication of highly efficient CO2 capture membranes.

Regulation of interlayer channels of graphene oxide nanosheets in ultra-thin Pebax mixed-matrix membranes for CO2 capture

For the application of carbon capture by membrane process, it is crucial to develop a highly permeable CO2-selective membrane. In this work, we reported an ultra-thin polyether-block-amide (Pebax) mixed-matrix membranes (MMMs) incorporated by graphene oxide (GO), in which the interlayer channels were regulated to optimize the CO2/N2 separation performance. Various membrane preparation conditions were systematically investigated on the influence of the membrane structure and separation performance, including the lateral size of GO nanosheets, GO loading, thermal reduction temperature and time. The results demonstrated that the precisely regulated interlayer channel of GO nanosheets can provide rapidly CO2-selective transport channels due to the synergetic effects of size sieving and preferential adsorption. The GO/Pebax ultra-thin MMMs exhibited CO2/N2 selectivity of 72 and CO2 permeance of 400 GPU (1 GPU = 10–6 cm3(STP)·cm–2·s–1·cmHg–1), providing a promising candidate for CO2 capture.

Pore-optimized MOF-808 made through a facile method using for fabrication of high-performance mixed matrix composite CO2 capture membranes

Mixed matrix composite membranes (MMCMs) are considered as one of the potential directions for the development of CO2 capture membranes. Nevertheless, the high cost and the challenging nature of improving separation performance are significant obstacles that prevent MMCMs from being widely applied in practice. In this study, we developed a cost-effective modified pore-optimized MOF-808 (MOF-808@PVAm) and utilized it to fabricate high-performance CO2 capture MMCMs. Specifically, MOF-808 and polyvinylamine (PVAm) were cross-linked by γ-(2,3-epoxypropoxy) propytrimethoxysilane (KH-560), which improved the pore structure characteristics of MOF-808 and led to high-performance MMCMs. For 2 bar feed gas (CO2/N2, 15/85), the MMCM with 33.33 wt.% MOF-808@PVAm loading displayed remarkable CO2 permeance of 2753 GPU and selectivity of 181. The prepared MMCM demonstrated good operational stability in simulated flue gas and exhibited potential for application in various gas purification fields (CO2/CH4, CO2/H2) through gas permeation tests.

PIM-based mixed matrix membranes containing covalent organic frameworks/ionic liquid composite materials for effective CO2/N2 separation

The development of high-performance CO2 capture membranes is an urgent requirement to combat the greenhouse effect and climate change. Covalent organic frameworks (COFs) with highly ordered porous structure and modifiable pore environment shows substantial potential in the field of membrane separation. Nevertheless, the scarce affinity sites and large pore diameters of COFs may limit their effect on gas separation in membranes. In the present work, TPB-DMTP-COF was modified with imidazolium-based ionic liquid [Emim][Tf2N] (IL) to remedy such disadvantages of COFs and then the mixed matrix membranes (MMMs) were prepared by introducing IL@COF into PIM-1. The IL modification not only can endow the TPB-DMTP-COF with better CO2 affinity and narrowed pore size, but also can further improved interfacial compatibility among PIM-1 and TPB-DMTP-COF. Therefore, the introduction of IL@COF into PIM-1 membrane can leads to an increase in CO2/N2 separation properties of the obtained membranes. Notably, 3.0 wt% IL@COF/PIM-1 MMMs show optimal CO2 permeability and CO2/N2 selectivity of 9137.7 Barrer and 20.2, respectively. Such high separation performance exceeds 2008 Robeson upper bound. Moreover, the resultant MMMs also exhibit favorable continuous operation stability. Overall, the combination of IL and COFs may provide a new inspiration for designing efficient CO2 separation MMMs.

Life cycle assessment of biostimulant production from algal biomass grown on piggery wastewater

Piggery wastewater has become a large source of pollution with high concentrations of nutrients, that must be managed and properly treated to increase its environmental viability. Currently, the use of microalgae for treating this type of wastewater has emerged as a sustainable process with several benefits, including nutrient recovery to produce valuable products such as biostimulants, and CO2 capture from flue gases. However, the biostimulant production from biomass grown on piggery wastewater also has environmental impacts that need to be studied to identify possible hotspots. This work presents the life cycle assessment by IMPACT 2002+ method of the production of microalgae-based biostimulants, comparing two different harvesting technologies (membrane in scenario 1 and centrifuge in scenario 2) and two different technologies for on-site CO2 capture from flue gases (chemical absorption and membrane separation). The use of membranes for harvesting (scenario 1) reduced the environmental impact in all categories (human health, ecosystem quality, climate change, and resources) by 30 % on average, compared to centrifuge (scenario 2). Also, membranes for CO2 capture allowed to decrease environmental impacts by 16 %, with the largest reduction in the resource category (∼33 %). Thus, the process with the best environmental viability was achieved in scenario 1 using membranes for CO2 capture, with a value of 217 kg CO2 eq/FU. In scenario 2 with centrifugation, the high contribution of the cultivation sub-unit in all impacts was highlighted (>75 %), while in scenario 1 the production sub-unit also had moderate contribution in the human health (∼35 %) and climate change (∼30 %) categories due to the lower concentration and high flow rates. These results were obtained under a worst-case situation with pilot scale optimized parameters, with limited data which would have to be further optimized at industrial-scale implementation. The sensitivity analysis showed a little influence of the parameters that contribute the most to the impacts, except for the transportation of the piggery wastewater to the processing plant in scenario 2. Because of the relevant impact of biostimulant transportation in scenario 1, centrifugation becomes more favourable when transportation distance is longer than 321 km.

Electrodepositing MOFs into laminated graphene oxide membrane for CO2 capture

Due to increased CO2 emissions from the combustion of fossil fuels, considerable efforts have been made in CO2 capture. The preparation of a membrane with higher mechanical qualities and large CO2 adsorption capacity, however, remains the main obstacle. Here, using an in-situ anodic electrodeposition approach, we grow HKUST-1 MOFs into the graphene oxide (GO) two-dimensional (2D) nanochannels. A three-stage mechanism for the confined growth of MOFs during electrodeposition has been proposed. Through the inventive layer-by-layer confinement structural growth, MOFs@GO composite membranes with hierarchical pore structure were prepared. An extremely high CO2 adsorption capacity of 194.1 cm3/g and CO2/N2 adsorption ideal selectivity of 276.5 were achieved at 273 K and atmospheric pressure because of the synergistic effect of nanoconfined HKUST-1 and GO. The composite membrane prepared by electrodeposition method can expose more metal active sites in the presence of hierarchical porous structures, thus enhancing the CO2 adsorption capacity. In addition, incorporating the HKUST-1 into GO nanochannels demonstrates 50.6% and 138.13% improvement in hardness and elastic modulus over pristine GO membrane, respectively. This provides a promising method for developing high-performance CO2 capture membrane system under normal temperature and pressure conditions. It is also generally applicable for growing other MOFs@GO composite membranes, such as Cu-BDC@GO and Cu-BDC-NH2@GO membranes, respectively, and more suitable for large-scale industrial production.

Efficient CO2 separation by ionic liquid nanoconfined in ultra-thin TCOH@Pebax-1657 MMM

Global climate change has continued to intensify in recent years, and the low efficiency of carbon emission reduction has become an important issue for many countries. Membrane separation technology has gained popularity in CO2 capture due to its ease of operation, environmental friendliness, and smaller area, etc. Two-dimensional (2D) sheet materials are one of the most promising materials for membrane separation technology. MXene has been used for gas separation because of its advantages such as high aspect ratio, excellent flexibility, and rich functional group surface. However, the stacking of massive MXene nanosheets lead to gas transport channel obstruction, causing the gas permeance to decrease. Herein, the hydroxylation of MXene was treated to obtain alkaline MXene nanosheets (TCOH) in this work. The stabilised TCOH and Pebax-1657 were used to make a mixed matrix membrane (MMM), while 1-ethyl-3-methylimidazolyl acetate ([EMIm][AcO], IL) was nanoconfined in the 2D channel of ultra-thin TCOH@Pebax-1657 MMM to construct a novel composite membrane for efficient CO2 capture. The TCOH@Pebax-1657/IL membrane prepared in this experiment has high CO2 permeance and the selectivity of CO2/N2, CO2/CH4 at the IL concentration of 35 wt%. In addition, the film has shown excellent thermal stability and durability over long periods of testing. Since TCOH is rarely used in the field of gas separation, the study will provide fresh idea for the preparation of highly efficient CO2 capture membranes.

Chemical topology molecular engineering of CO2-philic membranes toward highly efficient carbon capture

Membrane gas separation processes represent a crucial platform for achieving carbon neutral climate goals. CO2-philic membranes offer excellent solubility selectivity due to their high affinity, thereby allowing the separation of gas fractions with similar molecular sizes or smaller than CO2 molecules. This level of separation is difficult to achieve with conventional diffusion-dominated separation membranes. However, the gas permeability of PEO membranes is often hampered by dense chain packing and crystallization behavior. To overcome this challenge, we employed a molecular engineering approach to develop a unique PEO membrane with a hyperbranched chemical topology connection. The packing density of the polymer chains was effectively regulated by employing cross-linker molecules with distinct spatial configurations, while the free volume fraction was successfully reinforced. This unique molecular engineering strategy led to the creation of a PEO membrane exhibiting superior performance that surpassed the limit of the 2019 upper-bound line. This work demonstrated a molecular design strategy for the precise control of structural attributes in crosslinked PEO networks, offering an alternative solution for developing CO2 capture membranes and enabling further opportunities for rational membrane material design.