Gas permeability of cross-linked poly(ethylene-oxide) based on poly(ethylene glycol) dimethacrylate and a miscible siloxane co-monomer

Pure gas permeability coefficients of a series of copolymers based on polar, hydrophilic poly(ethylene glycol) dimethacrylate, n = 14 (PEGDMA) and siloxane-based co-monomer, [methyl bis(trimethylsiloxy)silyl] propyl glycerol methacrylate (SiGMA) are reported. SiGMA is miscible with PEGDMA and able to form homogeneous films. SiGMA contains a bulky siloxane-based end group, which acts to increase permeability, and an -OH pendant group, which increases miscibility with polar co-monomers, such as PEGDMA. As the SiGMA content in these copolymers increases to 53 vol%, CO₂ permeability increases from 95 to 255 barrer, while CO₂/N₂ and CO₂/H₂ pure gas selectivities decrease from 58 to 20 and 6.4 to 3.2, respectively. At the same time, fractional free volume of the copolymer increases from 0.118 to 0.140. Comparisons to a similar copolymer system are made to rationalize the permeability and selectivity trends of this series of copolymers.     

Gas transport and structural features of sulfonated poly(phenylene oxide)

The effect of ionomer structure on gas transport properties of membranes was investigated. For this purpose physical and transport properties of poly(phenylene oxide) (PPO) and its sulfonated derivative (SPPO) were compared. SPPO has a more rigid structure and a lower free volume, which determines low gas permeability and high permselectivity. Gas transport properties of two types of SPPO—PPO composite membranes with top layers prepared from solutions in methanol or N,N-dimethylacet-amide (DMA) were investigated. The use of SPPO solution in DMA leads to the formation of membranes with higher gas permeability. It was shown that DMA is a morphologically active solvent for SPPO. Strong complexes of SPPO with DMA are formed in solution and retained upon transition into the condensed state. The plasticizing effect of DMA on SPPO determines the high gas permeability of the membranes and is in agreement with their mechanical properties. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1439–1443, 1997     

Gas permeation properties of a composite membrane filled with poly(ethylene oxide) into a porous membrane

The permeability coefficients of O₂, N₂, and CO₂ gases at 25°C were examined for composite membranes that were prepared by filling poly(ethylene oxide)(PEO) with different molecular weights into a porous membrane. The permeability coefficients of O₂, N₂, and CO₂ were 2 × 10⁻¹⁰ – 4 × 10⁻¹⁰, 5 × 10⁻¹¹ – 9.5 × 10⁻¹¹, and 6 × 10⁻¹⁰ – 1 × 10⁻⁹ (cm³ STPcm/cm² s cmHg), respectively. The higher permeability coefficients of CO₂ are explained in terms of high solubility of CO₂ in filled PEO. The permeability coefficient of CO₂ was affected by the degree of crystallinity of PEO in the composite. On the other hand, there was little effect of crystallinity on O₂ and N₂ permeability coefficients. Some probable relationships between selectivities of O₂ to N₂ and CO₂ to N₂ and the degree of crystallinity of PEO were observed. The CO₂ gas permeability coefficients of the composite membrane for PEO50000 (M_w = 5 × 10⁴) showed a marked change due to melting or crystallization of PEO. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2733–2738, 1999     

Preparation of poly(acrylic acid)/poly(vinyl alcohol) membrane for the facilitated transport of CO2

Poly(acrylic acid) (PAA)/poly(vinyl alcohol) (PVA) membrane was prepared for the facilitated transport of CO₂. The carrier of CO₂ was monoprotonated ethylenediamine and was introduced in the membrane by ion exchange. The ion‐exchange capacity of the membrane was 4.5 meq/g, which was much higher than that of the Nafion 117 membrane. The membrane was highly swollen by the aqueous solution. Much higher selectivity of CO₂ over N₂ and higher CO₂ permeability were obtained in the PAA/PVA membrane than in the Nafion membrane because of the higher ion‐exchange capacity and solvent content. The highest selectivity was more than 1900 when the CO₂ partial pressure in the feed gas was 0.061 atm. Effects of ion‐exchange capacity, membrane thickness, and annealing temperature in conditions of membrane preparation on membrane performance were investigated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 936–942, 2001     

Measurement of transport properties of poly(methylmethacrylate-co-methacrylic acid) ion-containing membranes

Several membranes prepared from poly(methylmethacrylate-co-methacrylic acid) and its Li⁺ and Zn²⁺ ionomers were tested for NaCl, creatinine and urea permeability. The permeabilities of the membranes were explained on the basis of pore contents determined from their scanning electron microscope micrographs. All the membranes showed higher permeabilities during the first 2 hours of experimentation. Introduction of Zn²⁺ ions into the copolymer as crosslinking agent did not have much effect on the membrane properties but the properties of the copolymer were modified.     

Preparation of poly(phthalazinone ether sulfone ketone) hollow fiber membrane for gas separation

Poly(phthalazinone ether sulfone ketone) (PPESK) asymmetric hollow fiber membranes for gas separation were prepared by dry/wet phase inversion technique. The effects of various preparation conditions such as solvent, nonsolvent-additives(NSA), PPESK concentration, and air gap on the membrane performance were studied. The heat resistance of the PPESK hollow fiber membrane was also examined. The hollow fiber membrane prepared from solvent with stronger solubility showed low gas permeation and high O₂/N₂ selectivity due to the denser skin layer. Hollow fiber membrane made from PPESK/DMAc/EtOH/THF system had thicker skin layer than that made from PPESK/DMAc/GBL system with the same ratio of near-to-cloud-point of NSA, which resulted in the higher O₂/N₂ selectivity. Along with the increase of NSA content, the gas permeation increased and the O₂/N₂ selectivity decreased. The O₂/N₂ selectivity of hollow fiber membranes made from PPESK/DMAc/GBL and PPESK/DMAc/EtOH/THF systems were 4.9 and 4.8 respectively, when the membrane forming systems contained appropriate content of NSA. The high polymer concentration resulted in low gas permeation and high O₂/N₂ selectivity. When the air gap was excessively long, the membrane performance dropped because of the damage to the dense skin layer. There was no significant drop on the membrane performance when the operation temperature was elevated to 90°C. The average O₂/N₂ selectivity was higher than 3.0 at 70°C during a long period of 55 days' test time. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Separation of SF6 from Binary Mixtures with N2 Using Commercial Poly(4-Methyl-1-Pentene) Films

Systematic studies on gas permeation of pure SF₆ and N₂ as well as their mixture in poly(4-methyl-1-pentene) (PMP) at different temperatures and pressures, using commercially available thin PMP films, are reported in this article. The effective separation of SF₆ from binary mixtures with N₂ is critical for the proposed replacement of pure SF₆, used as an insulating gas in high power industry, by the mixtures of these two gases. This replacement is driven by the fact that SF₆ is the most potent greenhouse gas, with a global warming potential of 22,200 times that of CO_2. The experiments with a 1:1 mixture of N₂ and SF₆ revealed the permselectivity of PMP as high as 476 with the corresponding N₂ permeability coefficient of 7.6 Barrer. These properties, which are much better than those of other glassy polymers considered for this separation, were not affected by a long-term exposure to SF₆, which indicates the excellent resistance of PMP to plasticization by this gas. Using a single stage membrane system utilizing the PMP membrane would allow separating the above gas mixture into a 99% pure SF₆ product with the corresponding recovery rate of SF₆ greater than 99%.     

气体膜分离技术及应用

简要介绍了有关气体膜分离的基本原理、材料及其在氢气分离回收、空气分离和酸性气处理中的应用,并对气体膜分离的发展前景提出了自己的见解。     

Gas transport property of homo- and copolyimides from isomeric thiaphthalic dianhydride and oxydianiline

Gas transport properties of homo- and copolyimides prepared from 3,3′,4,4′- and 2,2′,3,3′-thiaphthalic dianhydride (p-TDPA and m-TDPA, respectively) with 4,4-oxydianiline (ODA) were investigated. The fractional free volume of m-TDPA-ODA is larger than that of p-TDPA-ODA, and the chain segmental mobility of the former is lower than that of the latter. The permeability coefficients of m-TDPA-ODA to H₂, CO₂, and O₂ are more increased by 48, 69 and 75%, at 30°C and 10 atm, respectively, than those of p-TDPA-ODA; but the permselectivities of m-TDPA-ODA for H₂, CO₂, and O₂ toward N₂ are more decreased by 33, 77, and 26%, respectively, than those of p-TDPA-ODA. The permeability coefficients and the diffusion coefficients of the copolyimides can be described by the following equations: log P = Φ_p log P_p + Φ_m log P_m and log D_a = Φ_p log(D_a)p + Φ_m log(D_a)_m, respectively. The variation of the permselectivity is controlled predominantly by diffusivity selectivity. These observations are interpreted in terms of variations in the fractional free volume of polyimides. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1821–1826, 1997     

气体膜分离技术的进展及其应用

介绍了气体分离膜材料的种类;叙述了介绍了气体膜分离技术在分离空气制备富氧、富氮,水蒸气、有机蒸汽的分离和氢气回收等工业领域的应用.介绍了气体膜分离技术的研究进展,并提出了我国气体膜分离技术发展方向.     

膜法气体除湿的研究进展

气体除湿在很多领域内具有重要的意义,传统除湿方式的不足日益凸显,需要进行改善和革新。介绍了膜法除湿的类型,以及膜组件的类型和特点,总结了膜法除湿操作条件对除湿效率的影响,对国内膜法除湿技术应用和发展进行了展望。     

Gas transport properties of CoAlPO4‐5/PC membranes

The transport phenomena of oxygen and nitrogen across a pure polycarbonate (PC) and CoAlPO₄‐5/PC membranes were studied. Various CoAlPO₄‐5 membranes with different cobalt content were added to polycarbonate membranes to improve the gas transport performance. Oxygen and nitrogen isotherms were studied. Solubility of oxygen and nitrogen was greatly increased by adding CoAlPO₄‐5 to the membranes, which also resulted in a higher solubility ratio of oxygen to nitrogen. It might be that a pinhole of the membrane caused the increase in diffusivity and a decrease in selectivity when excess CoAlPO₄‐5 was added. The results also showed that CoAlPO₄‐5 with a higher cobalt content would more effectively increase the gas solubility, but make only a minor change in the solubility ratio of oxygen to nitrogen. It was found that the increase in oxygen to nitrogen selectivity was mainly due to an increased diffusivity ratio of oxygen to nitrogen when CoAlPO₄‐5 was added into the membranes. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 89–95, 2000     

气体膜分离的进展及在石油化工中的应用

综述了气体膜分离技术在膜组件和膜材料方面的进展及在石油化工领域中的应用。     

Preparation of polyelectrolyte complex membranes based on sodium cellulose sulfate and poly(dimethyldiallylammonium chloride) and its permeability properties

In this study, polyelectrolyte complex (PELC) membranes prepared by the simultaneous interfacial reaction between aqueous solutions of sodium cellulose sulfate (NaCS) as polyanion and poly(dimethyldiallylammonium chloride) (PDMDAAC) as polycation were proposed. The preparation conditions were optimized. The influence of two important factors, molecular weight (MW) of PDMDAAC and reaction time on the membrane formation procedure and permeability was investigated. Membranes with the preparation conditions as NaCS 3.5% (w/v), PDMDAAC (MW = 200–350 kDa) 7.0% (w/v), the reaction time 30 min, hold a favorable performance, and steady state in water flux experiment. To testify the feasibility of the membrane used in salt separation, membrane performances and selectivity of the inorganic salts as well as their relations to the preparation conditions, the operation parameters, the species of inorganic salts, etc., were investigated in the pressure‐driven experiments. The results showed that this single‐layer PELC membrane afforded higher rejections of divalent ions (SO) to that of monovalent ions (Cl⁻), which indicated the potential application of this membrane system in the salt rejection process. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effects of polymerization conditions on the properties of poly(furfuryl alcohol) composite membranes

Poly(furfuryl alcohol) (PFA) composite membranes were prepared by polymerization of furfuryl alcohol (FA) using sulfuric acid (H₂SO₄) as the catalyst and polysulfone ultrafiltration membrane as the substrate. The membrane samples were characterized by ATR‐IR, TGA, SEM, and gas permeation technique. The effects of synthesis conditions including the FA/H₂SO₄ molar ratio, polymerization temperature, and the type of solvent on the chemical structure, surface morphology, and gas permeation properties of PFA composite membranes were studied. Our results showed that the suitable synthesis conditions for the preparation of PFA composite membranes with smooth surfaces and uniform structure include (1) FA/H₂SO₄ molar ratios: 74‐300, (2) polymerization temperatures: 80–100°C, and (3) solvents: ethanol and acetone. The PFA composite membrane prepared with a FA/H₂SO₄ molar ratio of 250, a polymerization temperature of 80°C and ethanol as the solvent exhibited the highest H₂/N₂ ideal selectivity ( $ {\rm{\alpha }}_{{\rm{H}}_{\rm{2}} {\rm{/N}}_{\rm{2}} } = 24.9 $ ), and a H₂ permeability of 206 Barrers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and properties of amphiphilic poly(ethylene oxide)-grafted cardo poly(aryl ether sulfone) copolymers

A series of comb-type amphiphilic copolymers (PES-g-PEO) with a stiff poly(aryl ether sulfone) backbone and flexible PEO side chains was synthesized via a “grafting onto” technique. By controlling the monomer feed ratios, high molecular weight copolymers with a range of PEO side chain content were prepared and used to form tough and flexible membranes. The PES-g-PEO membranes displayed high thermal stability (T_d > 230 °C) and good mechanical properties. The water contact angles of the PES-g-PEO membranes ranged from 60.5° to 66.7°, 20° lower than those of poly(aryl ether sulfone) membranes (82-86°), indicating that the PEO side chains improved the hydrophilicity of the membranes. Wide-angle X-ray diffraction results indicated that the PES-g-PEO membranes possessed an amorphous structure, that is, crystallization of the PEO side chains did not occur. The Li-ion conductivity reached 2.26 × 10⁻⁴ S/cm at room temperature, much higher than that of the pure PEO-based system (10⁻⁶ S/cm), due to the presence of the amorphous PEO side chains between the PES backbones, which provided an effective Li-ion transport pathway.     

高聚物/陶瓷复合膜的气体渗透及分离行为

以实验室制备成功的SR／Ceramic和PPESK／Ceramic复合膜为基础,对O2、N2、H2、CO、CO2、CH4等气体在高聚物／陶瓷复合膜上的渗透性能进行研究;在较宽的温度范围内考察了复合膜的使用效果,并获得各种气体的渗透活化能及其与气体临界温度的关系;渗透活化能随临界温度的增大而增低。同时,以空气分离体系为对象,考察了膜分离器的操作参数q和pr对膜分离系统过程行为的影响;实验结果和理论分析一致。     

Synthesis,properties, and gas permeation performance of cardo poly(arylene ether sulfone)s containing phthalimide side groups

Novel bisphenol monomers ( 1a‐d ) containing phthalimide groups were synthesized by the reaction of phenolphthalein with ammonia, methylamine, aniline, and 4‐tert‐butylanilne, respectively. A series of cardo poly(arylene ether sulfone)s was synthesized via aromatic nucleophilic substitution of 1a‐d with dichlorodiphenylsulfone, and characterized in terms of thermal, mechanical and gas transport properties to H₂, O₂, N₂, and CO₂. The polymers showed high glass transition temperature in the range 230–296°C, good solubility in polar solvents as well as excellent thermal stability with 5% weight loss above 410°C. The most permeable membrane studied showed permeability coefficients of 1.78 barrers to O₂ and 13.80 barrers to CO₂, with ideal selectivity factors of 4.24 for O₂/N₂ pair and 28.75 for CO₂/CH₄ pair. Furthermore, the structure–property relationship among these cardo poly(arylene ether sulfone)s had been discussed on solubility, thermal stability, mechanical, and gas permeation properties. The results indicated that introducing 4‐tert‐butylphenyl group improved the gas permeability of polymers evidently. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Gas transport properties of polybenzoxazinoneimides and their prepolymers

Three types of imide-containing polyamic acids (polybenzoxazinoneimide prepolymers), namely, a homopolymer, a copolymer, and a polymer-metal complex were synthesized and used for homogeneous membranes preparation. These membranes exhibited good physico-mechanical properties and also chemical and hydrolytical stability. Their gas separation properties were measured and analyzed by correlation with macromolecular packing density. Polybenzoxazinoneimide membranes were prepared by heating prepolymer membranes to 220 °C. Difference between gas separation properties of membranes based on polybenzoxazinoneimides and those of their prepolymers was estimated. Gas transport properties of all novel membranes were compared with those of known membranes by using Robeson's diagram. It was established that a polybenzoxazinoneimide membrane including a polymer-metal complex is the most effective among membranes studied here.     

Synthesis of PEG‐functionalized poly(diphenylacetylene)s and their gas permeation properties

The polymerizations of 1‐(3‐methylphenyl)‐2‐(4‐trimethylsilyl)phenylacetylene ( 1a ) and 1‐(4‐methylphenyl)‐2‐(4‐trimethylsilyl)phenylacetylene ( 1b ) were carried out with TaCl₅‐n‐Bu₄Sn to give relatively high‐molecular‐weight polymers ( 2a and 2b ) (M_n > 5 × 10⁵). The obtained polymers were brominated by using benzoyl peroxide and N‐bromosuccinimide first, followed by substitution reaction of three types of polyethylene glycol. When diethylene glycol was used as a reagent on substitution reaction of meta‐substituted polymer, PEG‐functionalized poly(diphenylacetylene) with the highest content of oxyethylene unit [ 4a(2) ] was obtained, and the degree of substitution was 0.60. The degrees of substitution decreased to 0.15 and 0.08 when the polyethylene glycols with higher molecular weights were used. PEG‐substitution reaction to the para‐substituted polymers was difficult to proceed, and hence the degree of substitution was 0.18 even when diethylene glycol was used. The CO₂/N₂ separation factor of PEG‐functionalized polymer [ 4a(2) ] was as large as 28.8, although that of 2a was 7.41. The other PEG‐functionalized polymers also exhibited high CO₂ permselectivity, and their CO₂/N₂ separation factors were over 20. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009