Nanocomposite membranes were prepared by incorporation of commercial poly(ethylene glycol) functionalized polyoctahedral oligomeric silsesquioxanes (PEG-POSS) in two grades of poly(ether-block-amide) namely PEBAX ® MH 1657 and PEBAX ® 2533. Single gas permeabilities of N 2 , O 2 , CH 4 , H 2 , and CO 2 were measured using the time-lag method. CO 2 permeability increased two fold after incorporation of 30 wt% PEG-POSS in PEBAX ® MH 1657, while the selectivity was not significantly affected at 30 °C. Simultaneous enhancement in permeability and selectivity was observed up to 30 wt% loading of PEG-POSS in PEBAX ® 2533 at 30 °C. The effect of temperature upon CO 2 permeability and CO 2 selectivity over N 2 , O 2 , CH 4 and H 2 was studied between 30 ºC to 70 °C. Substantial influence upon the thermal transition of the polyether domain of both polymers was observed due to incorporation of PEG-POSS by differential scanning calorimetry (DSC). Atomic force microscopy was used to evaluate the impact of 30 wt% PEG-POSS loading upon the surface topography of both investigated grades of PEBAX ®. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to study the membrane morphology and the distribution of the nanofillers (PEG-POSS) in PEBAX ® membranes.

The present work reports on the gas transport behavior of mixed matrix membranes (MMM) which were prepared from multi-walled carbon nanotubes (MWCNTs) and dispersed within polymers of intrinsic microporosity (PIM-1) matrix. The MWCNTs were chemically functionalized with poly(ethylene glycol) (PEG) for a better dispersion in the polymer matrix. MMM-incorporating functionalized MWCNTs (f-MWCNTs) were fabricated by dip-coating method using microporous polyacrylonitrile membrane as a support and were characterized for gas separation performance. Gas permeation measurements show that MMM incorporated with pristine or functionalized MWCNTs exhibited improved gas separation performance compared to pure PIM-1. The f-MWCNTs MMM show better performance in terms of permeance and selectivity in comparison to pristine MWCNTs. The gas permeances of the derived MMM are increased to approximately 50% without sacrificing the selectivity at 2 wt.% of f-MWCNTs' loading. The PEG groups on the MWCNTs have strong interaction with CO2 which increases the solubility of polar gas and limit the solubility of nonpolar gas, which is advantageous for CO2/N2 selectivity. The addition of f-MWCNTs inside the polymer matrix also improved the long-term gas transport stability of MMM in comparison with PIM-1. The high permeance, selectivity, and long term stability of the fabricated MMM suggest that the reported approach can be utilized in practical gas separation technology.

The derived MMM were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and single gas permeation tests. Gas permeation measurements showed that MMM incorporated with modified and non-modified CNTs exhibited different gas separation performance. The f-MWCNT MMM show better performance compared to MMM with non-modified CNTs in terms of dispersion and permeability at 2 wt% f-MWCNTs loading without sacrificing selectivity. According to diffusivity and solubility data derived from the time-lag method, the PEG chains on MWCNTs show interaction with CO 2 as indicated by an increase of the solubility of the polar gas and a reduction of the solubility of non-polar gas, which is advantageous for CO 2 /N 2 separation. The mechanical properties and experimental sorption isotherms of CO 2 and N 2 of the f-MWCNTs/PIM MMM were enhanced as well. KeywordsMixed matrix membrane, Multi-walled carbon nanotubes, Polymer of intrinsic microporosity 1 1. Introduction:

Gas permeation characteristics of carbon nanomembranes (CNMs) from self-assembled monolayers are reported for the first time. The assembly of CNMs onto polydimethylsiloxane (PDMS) support membranes allows mechanical measurements under compression as well as determination of gas permeation characteristics. The results suggest that molecular-sized channels in CNMs dominate the permeation properties of the 1 nm thin CNMs.

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Conjugated microporous polymers (CMPs) have attracted much interest due to their intrinsic porosity, outstanding stability, and high variability. However, the processing of these materials for membrane application has been limited due to their insoluble nature when synthesized as bulk material. Here we report the synthesis of freestanding CMP-nanomembranes via layer-by-layer growth of a "click" based conjugated microporous polymer on a sacrificial substrate. After dissolution of the substrate the CMPnanomembrane can be transferred to porous substrates and continuously cover holes of up to 50 μm diameter. The CMPnanomembranes appear defect-free as inferred from high selectivity values obtained from gas permeation experiments and from electrochemical investigation in the presence of ferrocene. The presented synthesis method represents a versatile strategy to incorporate CMP materials in functional devices for membrane separation, catalysis, or organic electronics. C onjugated microporous polymers (CMP) are a class of microporous solids which have recently attracted wide interest due to their large surface areas, low densities, and the possibility to incorporate different kinds of functional groups in a modular fashion. 1 In contrast to related metal organic frameworks (MOF) 2−5 or covalent organic frameworks (COF) 6,7 which are formed through reversible reactions, CMPs are formed through high yielding irreversible reactions of rigid building blocks. The resulting CMP materials are amorphous and at the same time often show narrow pore size distribution. 8 The exceptional thermal and chemical stability goes well beyond that of MOFs and COFs and makes this class of porous materials particularly appealing for practical applications such as gas storage, catalysis, and molecular separation. 9,10 Among the numerous synthetic routes used in the past, click reaction chemistry has played a special role as a result of its ease of operation. The high purity and readily accessible products of click chemistry are particularly attractive to produce CMP materials. 11 Among the large variety of CMP applications, two-dimensional nanomembranes with a thickness below 10 nm exhibiting tunable pore sizes that can act as molecular sieves have a particularly large potential, since they are predicted to be ideal separation membranes with many advantages over bulk membranes. 12,13 However, the inert nature of most CMP materials causes severe, intrinsic challenges in their processing to yield large scale membranes. Indeed, only branched "soluble conjugated microporous polymers" (SCMPs) 14 and linear conjugated polymers of intrinsic microporosity (C-PIMs) 15 can be processed from solution. Usually CMPs are, in contrast to most polymers, not soluble in organic solvents, 1 and as a result, common processing techniques to fabricate polymer films from a solution such as spin coating cannot be applied.Considering the recent success in using layer-by-layer or quasi-epitaxial approaches for the fabrication of thin MOFlayers (SURMOFs) 16,17 we fabric...

a b s t r a c tQuaternary ammonium compounds are known to have extremely high affinity to carbon dioxide. Two new highly hydrophilic compounds containing one or two quaternary ammonium moieties attached to the reactive trimethoxy silane were synthesized and studied for physico-chemical and gas transport properties in the dry and wet environments. Both compounds in the form of blends with PEBAX ® MH 1657 showed high CO 2 solubility coefficients and high CO 2 /N 2 (up to 1500) and CO 2 /H 2 (up to 1350) solubility selectivity. The dry gas measurements revealed the presence of specific interaction with CO 2 resulting in strong binding of the gas molecule to the polymer active center resulting in increased solubility and decreased diffusion coefficients. At low temperatures CO 2 was irreversibly sorbed in the quaternary ammonium compound and was released only at temperatures higher than 60 • C. For the sample modified by co-hydrolysis with TEOS the temperature of 60 • C was found to be an additional transition point giving for H 2 , N 2 , O 2 and CO 2 break on the solubility coefficient Arrhenius plots. Measurements carried out with humid feed revealed up to 35-fold increase of gas permeability without CO 2 /N 2 and CO 2 /H 2 ideal selectivity loss compared to the dry gas measurements.