The novel cross-linker, poly(propylene glycol) block poly(ethylene glycol) block poly(propylene glycol) diamine (PPG/PEG/PPGDA), was employed to chemically cross-link Matrimid 5218 at room temperature. The cross-linking reaction process was monitored by FTIR. The XRD was used to indicate the changing of the polymer structure by cross-linking reaction. The effects of the cross-linking reaction on mechanical performance, gel content and H2, CO2, N2 and CH4 gas transport properties of the cross-linked Matrimid membranes were investigated. The cross-linked Matrimid membranes display excellent CO2 permeability and CO2/light gas selectivity compared with the uncross-linked Matrimid membrane. Finally, the potential application of the cross-linked Matrimid membranes for CO2/light gas separation was explored. 相似文献
Organic-inorganic hybrid materials were prepared by reacting 3-isocyanatopropyltriethoxysilane (IPTS) with hydroxyl terminated
poly(ethylene glycol) (PEG), poly(propylene glycol) (PPG) and poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene
glycol) (PEPG), followed by hydrolysis and condensation with acid catalysis. Composite membranes have been obtained by casting
hybrid sol on the microporous polysulfone substrate. The membranes were characterized by Fourier transform infrared (FT-IR),
13C NMR and 29Si NMR. The permeability coefficients of N2, O2, CH4 and CO2 were measured by variable volume method. The gas permeability coefficients increase with increasing molecular weight of the
polyethers. For the membranes containing PEG and PEPG, the higher values of CO2 permeability coefficients and CO2/N2 separation factors are due to the presence of ethylene oxide segments. In case of PEPG membranes, molecular weight has more
influence on CO2 permeability than the effect of facilitation by ethylene oxide. The addition of TEOS into hybrid sol results in the decrease
of all the gas permeability and does not affect the gas selectivity. PEG2000 membrane display the most performance among the
hybrid membranes investigated here. The best values observed are CO2 permeability of 94.2 Barrer with selectivity of 38.3 for CO2/N2 and 15.6 for CO2/CH4. 相似文献
Water soluble nonionic amphiphilic block copolymers based on hydrophilic poly(ethylene glycol) (PEG) and hydrophobic poly(propylene glycol) (PPG) were prepared. Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) copolymers, PEG-PPG-PEG, were prepared in the normal condition. The chemical composition and molecular weights of the prepared copolymers were determined from 1H NMR and GPC techniques. The surface properties of the prepared surfactants were determined by measuring the surface tension at different temperatures. The prepared nonionic surfactants were evaluated as demulsifiers for water in crude-oil emulsions that were pronounced at different ratios of crude oil: water at 318 K and 333 K. The experimental results showed that the dehydration rate of the prepared demulsifiers reached 100% based on demulsifier chemical compositions and concentrations. 相似文献
For preventing plasticization phenomenon, cross-linked Matrimid membranes were prepared. Matrimid membranes were immersed in a solution of 10% (w/v) ethylenediamine or hexamethylenediamine in methanol for preparation of cross-linked membranes. Using a gas separation membrane unit, permeability properties of pristine and modified membranes for pure gases (CO2 and CH4) were investigated. CO2 plasticization effect on permeability properties of the membranes is discussed. Modified membranes indicated smaller values of tensile strength than pristine membranes. Thermal gravimetric analysis showed that thermal resistance of modified membranes increased in a limited temperature range. In general, modified membranes were thermally stable for separation applications. Formation of amide groups in modified membranes was investigated by Fourier transform infrared spectroscopy analysis. 相似文献
Polymer of Intrinsic Microporosity (i.e. PIM-1) has been crosslinked thermally via nitrene reaction using polyethylene glycol biazide (PEG-biazide) as a crosslinker. The crosslinking temperature was optimized using TGA coupled with FT-IR spectroscopy. The dense membranes containing different ratios of PIM-1 to PEG-biazide were cast from chloroform solution. Crosslinking of PIM-1 renders it insoluble even in excellent solvents for the uncrosslinked polymer. The resulting crosslinked membranes were characterized by FT-IR spectroscopy, TGA and gel content analysis. The influence of crosslinker content on the gas transport properties of PIM-1, its density and fractional free volume (FFV) were investigated. Compared to the pure PIM-1 membrane, the crosslinked PIM-1 membranes showed better gas separation performance especially for CO2/N2, CO2/CH4 and propylene/propane (C3H6/C3H8) gas pairs and as well as suppressed penetrant-induced plasticization under high CO2 pressure. 相似文献
A series of amine-containing polyurethanes and poly(urethane-urea)s based on 4,4′-diphenylmethane diisocyanate and either poly(ethylene glycol) of molecular weights 400 or 600 were prepared as gas separation membranes. The amine functional groups of N-methyldiethanolamine (MDEA) and/or tetraethylenepentamine (TEPA) were introduced into the hard segment as a chain extender. The gas transport data of He, H2, O2, N2, CH4 and CO2 in these polymer membranes were determined by using the Barrer's high-vacuum technique and the time-lag method. The restriction of chain mobility has been shown by the formation of hydrogen bonding in the soft segment and hard-segment domains, resulting in the increase in the density, glass transition temperature of soft segments (Tgs). The separation mechanism of various gas pairs used in industrial processes is also discussed. Effect of pressure on permeability of the gases above and below Tgs was studied. It was found that the gas permeability increased or decreased with upstream pressure above Tgs, and should be described by a modified free-volume model. On the other hand, the condensable CO2 exhibits a minimum permeability at a certain upstream pressure below Tgs. The permeability of He and H2 were pressure independent above and below the Tgs. 相似文献
The structural orientation of an amphiphilic crystalline polymer to a highly ordered microphase‐separated lamellar structure on a hydrophobic surface is presented. It is formed by the surface graft polymerization of poly(ethylene glycol)behenyl ether methacrylate onto poly(trimethylsilyl) propyne in the presence of allylamine. In particular, allylamine plays a pivotal role in controlling the crystalline phase, configuration, and permeation properties. The resulting materials are effectively used to improve the CO2 capture property of membranes. Upon the optimization of the reaction conditions, a high CO2 permeability of 501 Barrer and a CO2/N2 ideal selectivity of 77.2 are obtained, which exceed the Robeson upper bound limit. It is inspiring to surpass the upper bound limit via a simple surface modification method. 相似文献
The objective of this study was to synthesize rubbery polymers with a high H2S/CH4 selectivity for possible use as membrane materials for the separation of H2S from ‘low-quality’ natural gas. Two poly(ether urethanes), designated hereafter PU1 and PU3, and two poly(ether urethane ureas), designated PU2 and PU4, were synthesized and cast in the form of ‘dense’ (homogeneous) membranes. PU1 and PU2 contained poly(propylene oxide) whereas PU3 and PU4 contained poly(ethylene oxide) as the polyether component. The permeability of these membranes to two ternary mixtures of CH4, CO2, and H2S was measured at 35°C, and for a PU4 membrane also at 20°C, in the pressure range from 4 to 13.6 atm (4.05–13.78×105 Pa). PU4 is a very promising membrane material for H2S separation from mixtures with CH4 and CO2, having a H2S/CH4 selectivity greater than 100 at 20°C as well as a very high permeability to H2S. Permeability measurements were also made with commercial PEBAXTM membranes for comparison. The possibility of upgrading low-quality natural gas to US pipeline specifications for H2S and CO2 by means of membrane processes utilizing both highly H2S-selective and CO2-selective polymer membranes is discussed. 相似文献
The branching and cross-linking of poly(ethylene terephthalate) were investigated using two chain extenders: glycidyl methacrylate-styrene copolymer (GS) and poly(butylene terephthalate)-GS (PBT-GS) in order to improve the melt viscosity and melt strength of poly(ethylene terephthalate). An obvious increase in torque evolution associated with chain extending, branching and cross-linking was observed during the process. The properties of modified poly(ethylene terephthalate) were characterized by intrinsic viscosity and insoluble content measurements, rheological and thermal analysis. The intrinsic viscosity and rheological properties of modified PET were improved significantly when using PBT-GS, indicating that PBT-GS should be a better chain extender. Good foaming of poly(ethylene terephthalate) materials were obtained using supercritical CO2 as blowing agent. The average cell diameter and cell density were 61 μm and 1.8 × 108 cells/cm3, respectively. 相似文献
New thermoresponsive crosslinked hydrogels with controlled multiblock copolymer structure were prepared from equimolar amounts of α,ω-diamino poly(propylene glycol)s with molecular weights (MW) 230, 400, and 2,000 g mol?1 and diepoxy-terminated poly(ethylene glycol)s of approximate MW 1,000; 2,000; and 4,000 g mol?1. Their thermoresponsive character was investigated on the 10–70 °C interval, while the swelling behavior was tested at 21, 37, and 50 °C. All hydrogels displayed temperature sensitivity, but a volume phase transition was noticed only in the case of poly(propylene glycol) (PPG)2000-containing hydrogels. The volume phase transition temperature (TVPT) depended on the MW of the hydrophilic poly(ethylene glycol) (PEG) chains attached to the PPG2000 block, as well as on the added salts. Longer PEG blocks determined a shift of TVPT towards higher values, while the influence of the salt added was in agreement with the Hofmeister series, except for NaH2PO4 which determined the destruction of the hydrogel network. The equilibrium swelling degree depended on the MW of both PEG and PPG blocks, as well as on temperature. The analysis of the swelling process indicated a modification of the gel characteristics with temperature and second-order kinetics for the water penetration into the hydrogel. 相似文献
Previous interpretations of gas transport data in crosslinked networks have been hindered by an inability to accurately control and evaluate the network parameters. We have recently prepared a series of model networks by reacting poly(propylene glycol) with a triisocyanate crosslinking agent. The poly(propylene glycol)s had narrow molecular weight distributions and average molecular weights between 425 and 3000, so the resulting networks had uniform average molecular weights between crosslinks. Hydrogen and carbon monoxide permeabilities in membranes formed from these networks increase with decreasing crosslink density. These results indicate increased cooperative molecular motions in the networks with longer average chain lengths between crosslinks. Increasing the average molecular weight between crosslinks also reduces the discrimination between these two gases so that the separation factors decrease. For networks prepared from mixtures of poly(propylene glycol)s with different molecular weights the gas permeabilities (but not the separation factors) depend on the molecular weight distribution. 相似文献
Achieving high membrane performance in terms of gas permeance and carbon dioxide selectivity is an important target in carbon capture. Aiming to manipulate the channel affinity towards CO2 to implement efficient separations, gas separation membranes containing CO2‐philic and non‐CO2‐philic nanodomains in the interlayer channels of graphene oxide (GO) were formed by intercalating poly(ethylene glycol) diamines (PEGDA). PEGDA reacts with epoxy groups on the GO surface, constructing CO2‐philic nanodomains and rendering a high sorption capacity, whereas unreacted GO surfaces give non‐CO2‐philic nanodomains, rendering low‐friction diffusion. Owing to the orderly stacking of nanochannels through cross‐linking and the heterogeneous nanodomains with moderate CO2 affinity, a GO‐PEGDA500 membrane exhibits a high CO2 permeance of 175.5 GPU and a CO2/CH4 selectivity of 69.5, which is the highest performance reported for dry‐state GO‐stacking membranes. 相似文献
A method is developed for the synthesis of the graft copolymer polyvinyltrimethylsilane-graft-poly(ethylene glycol) via the interaction of a brominated polymer with the methyl ether of a low-molecular-mass poly(ethylene glycol). Graft copolymer samples containing up to 79 wt % poly(ethylene glycol) are synthesized through this method. The properties of the graft copolymers and blends formed on their basis with a specially synthesized low-molecular-mass PEG derivative with a terminal trimethylsilyl group are investigated. Physical blends are prepared in order to increase the content of ethylene oxide groups while the film-forming properties of the composite materials are preserved. As shown by structural studies, the graft copolymers are amorphous single-phase systems, while the related blends are two-phase disperse systems, in which one phase is enriched in polytrimethylvinylsilane and the other is enriched in PEG. Studies of the gas-transport behavior of the samples reveal that the introduction of PEG, in contrast to the nonselective initial polymer, results in the formation of PVTMS-based materials that are selective for CO2 in mixtures with H2. 相似文献
In the present work, membranes from commercially available Pebax® MH 1657 and its blends with low molecular weight poly(ethylene glycol) PEG were prepared by using a simple binary solvent (ethanol/water). Dense film membranes show excellent compatibility with PEG system up to 50 wt.% of content. Gas transport properties have been determined for four gases (H2, N2, CH4, CO2) and the obtained permeabilities were correlated with polymer properties and morphology of the membranes. The permeability of CO2 in Pebax®/PEG membrane (50 wt.% of PEG) was increased two fold regarding to the pristine Pebax®. Although CO2/N2 and CO2/CH4 selectivity remained constant, an enhancement of CO2/H2 selectivity (∼11) was observed. These results were attributed to the presence of EO units which increases CO2 permeability, and to a probable increase of fractional free-volume. Furthermore, for free-volume discussion and permeability of gases, additive and Maxwell models were used. 相似文献
We report the solubility of carbon dioxide in four physical solvents and compare our data to predicted phase behavior using the conductor-like screening model for real solvents (COSMO-RS) formalism. The solubility data are presented in pressure-composition (Px) diagrams as well as Henry's law coefficients on a wt% basis at 298.15 K. The oligomers presented in this study are poly ethylene glycol di-methyl ether (PEGDME), perfluoro polyether (PFPE), poly di-methyl siloxane (PDMS), and poly propylene glycol di-methyl ether (PPGDME), which is a new solvent designed for this application by our group. These oligomers had 2–5 repeat units. We assess these four oligomers for capturing CO2 from high-pressure streams. The COSMO-RS formalism is able to qualitatively and to some extent quantitatively describe solubilities of CO2 in each of the oligomers. 相似文献
Low‐molecular‐weight poly(ethylene glycol) (PEG) is deliberately incorporated into synthesized swellable poly(ethylene oxide) (PEO) membranes via a facile post‐treatment strategy. The membranes exhibit both larger fractional free volume (FFV) and a higher content of CO2‐philic building units, resulting in significant increments in both CO2 permeability and CO2/H2 selectivity. The separation performance correlates nicely with the microstructure of the membranes. This study may provide useful insights in the formation and mass transport behavior of highly efficient polymeric membranes applicable to clean energy purification and CO2 capture, and possibly bridge the material‐induced technology gap between academia and industry.