Membranes aromatic polyimides

Makino, H., Y. Kusuki, H. Yoshida, and A. Nakamura, Process for Preparing Aromatic Polyimide Semipermeable Membranes, U.S. Patent No. 4,378,324, March 1983. 

Asano, N., Aoki, M., Suzuki, S., Miyatake, K., Uchida, H. and Watanabe, M. 2006. Aliphatic/aromatic polyimide ionomers as a proton conductive membrane for fuel cell applications. Journal of the American Chemical Society 128 1762-1769. 

Y. Kusuki, T. Yoshinaga and H. Shimazaki, Aromatic Polyimide Double Layered Hollow Filamentary Membrane and Process for Producing Same, US Patent 5,141, 642 (August, 1992). 

Fluorinated polyimides have achieved great importance as barrier materials during the last few years. Many experimental polyimides prepared from fluorine-containing monomers, mainly novel diamines, show an advantageous balance of permeability and selectivity for technical gases and vapours, which makes them very attractive for the fabrication of permselective membranes [119]. This is an application field showing very rapid expansion, where there exists a strong demand for new polymeric materials, and where soluble aromatic polyimides are considered as a real alternative [136-146]. 

A nonporous aromatic polyimide membrane that is selectively permeable to H2, H, and H O has also been used for water vapor removal before the sample enters the ICP-MS [32]. Molecular analyte oxide ion signals were reduced approximately two orders of magnitude and O-containing polyatomic ions, such as ArO+ and C10+, were reduced by one to two orders of magnitude. 

Monsanto and Ube (Japan) developed membrane processes for purification of hydrogen gas mixtures. This process is based on the selective diffusion of hydrogen through semi-permeable membranes in the form of hollow fibers. The Monsanto PRISM separator process (owned by Air Products as of 2004) uses a polysulfone fiber whereas Ube uses an aromatic polyimide fiber.46... 

Okamoto K, Wang H, Ijyuin T, Fujiwara S, Tanaka K, and Kita H. Pervaporation of aromatic/non-aromatic hydrocarbon mixtures through crosslinked membranes of polyimide with pendant phosphonate ester groups. J Membr Sci 1999 157 97-105. 

Wang YC, Li CL, Huang J, Lin C, Lee KR, Liaw DJ, and Lai JY. Pervaporation of benzene/cyclohexane mixtures through aromatic polyimide membranes. J Membr Sci 2001 185 193-200. 

The aromatic polyimides, cited earlier, separate carbon dioxide over methane with a-valves of 150-160. Aromatic polyoxadiazoles have a-valves of 100-2 00.157 The permeability of one aromatic polyimide was improved by two to four orders of magnitude by carbonizing it on porous alumina,158 the final a-valve being 100. In this case, the final actual membrane was probably a porous carbon molecular sieve. Facilitated transport has also been used to increase the separation factor. A porous poly(vinylidene difluoride) membrane with ethanolamine or diethanolamine in the pores gave a separation factor of carbon dioxide over methane of 2000.159 Such a method is less energy-intensive than when an amine is used in the usual solvent method. 

Aromatic polyimides, containing trifluoromethyl groups, have been used to separate hydrogen over carbon monoxide, with a-values of 26-66 and hydrogen over methane with a-valves of 73-380.160 An a-valve of 22 was obtained with a membrane of a copolymer of methyl methacrylate and tris (trimethylsiloxy) y (met ha cry loxy)propyl] silane, in a process estimated to cost only 40% of the cost of the present cryogenic distillation.161... 

Ribeiro C. P., Freeman B. D., Kalika D. S., Kalakkunnath S. 2012. Aromatic polyimide and polybenzoxazole membranes for the fractionation of aromatic/aliphatic hydrocarbons by pervaporation. Journal of Membrane Science 390-391 182-193. 

A suitable polymer material for preparation of carbon membranes should not cause pore holes or any defects after the carbonization. Up to now, various precursor materials such as polyimide, polyacrylonitrile (PAN), poly(phthalazinone ether sulfone ketone) and poly(phenylene oxide) have been used for the fabrication of carbon molecular sieve membranes. Likewise, aromatic polyimide and its derivatives have been extensively used as precursor for carbon membranes due to their rigid structure and high carbon yields. The membrane morphology of polyimide could be well maintained during the high temperature carbonization process. A commercially available and cheap polymeric material is cellulose acetate (CA, MW 100 000, DS = 2.45) this was also used as the precursor material for preparation of carbon membranes by He et al They reported that cellulose acetate can be easily dissolved in many solvents to form the dope solution for spinning the hollow fibers, and the hollow fiber carbon membranes prepared showed good separation performances. 

On the one hand, linear aromatic polyimides have been generally used as electronic and aerospace materials because of their excellent mechanical strength, thermal, chemical and electronic/optic properties compared with other common amorphous polymers. Polyimides are also excellent membrane materials for gas separation due to their rigid chemical structures, allowing the production of larger functional free volume. Over the... 

Du Pont, a leader in reverse osmosis technology built around a unique class of tailored aromatic polyamides, was also an early leader in the gas separation field. Molecuiariy engineered aromatic polyimides were found by Du Pont to provide extraordinarily good flux arxl selectivity properties for hydrogen separations. POsttreatment processes for these membranes were rmt reported. 

In EP07708077A3 (Dabou et al. 1996), gas separation polymer membranes were prepared from mixtures of a polysulfone, Udel P-1700 and an aromatic polyimide, Matrimid 5218. The two polymers were proven to be completely miscible as confirmed by optical microscopy, glass transition temperature values and spectroscopy analysis of the prepared mixtures. This complete miscibility allowed for the preparation of both symmetric and asymmetric blend membranes in any proportion from 1 to 99 wt% of polysulfone and polyimide. The blend membranes showed significant permeability improvements, compared to the pure polyimides, with a minor change in the selectivity. Blend membranes were also considerably more resistant to plasticization compared with pure polyimides. This work showed the use of polysulfone-polyimide polymer blends for the preparation of gas separation membranes for applications in the separation of industrial gases. 

In 1908, aromatic polyimides were first reported by Bogert and Renstiaw [1]. Aromatic polyimides became well-known in 1950, after successful development of two-step polyimide synthesis by DuPont [2]. This class of polymers possesses a number of outstanding properties such as excellent thermal stability, mechanical strength, and electrical properties that have led to application in several fields from engineering thermoplastics to the aerospace and electronics industries, as well as for fibers and adhesives and in matrices for composite materials [3-5]. In addition, polyimides have high thermo-oxidative stability and chemical- and solvent-resistive properties, leading to many membrane-based applications... 

All of these approaches to making processable polyimides reduce several types of polymer interchain interactions, chain packing, and charge transfer electronic polarization interactions or charge transfer complex (CTC) formation. The current chapter presents a comprehensive review focusing on -C(CF3)2-and -CF3-based aromatic polyimides that have been developed between 2000 and 2010, such as low dielectric constant polymers, and well as membrane-based applications such as pervaporation, fuel cell, and gas separation. 

Polyimides are the most studied polymeric materials for membrane-based gas separation application. Although aromatic polyimides have received much attention as gas separation membrane materials, the polyimide family encompasses a large number of structural variants, and many studies on polyimide membranes indicate that separation properties can be tailored by using different dianhydride and diamine monomers. It was reported in the late 1980s that... 

C.P. Ribeiroa, B.D. Freemana, D.S. Kalikab, S. Kalakkunnath, Aromatic polyimide and poly-benzoxazole membranes for the fractionation of aromatic/ahphatic hydrocarbons by pervapora-tion, J. Membr. Sci. 390-391 (2012) 182-193. 

In 1995, Ni et al. studied the PVMR involving the reaction between valeric acid and ethanol to give ethyl valerate. A hydrophilic modified aromatic polyimide membrane and p-toluene sulfonic acid as catalyst were used. The integration in a membrane reactor of reaction and pervaporation allowed for obtaining a conversion rate of 95.2%. 

The earliest report on CMS membranes obtained from hollow fiber polymeric membranes appears to be from Koresh and Soffer (1983) and Soffer et al. (1987). By comparing CMS membranes derived from different polymeric membranes, Jones and Koros (1994a) found that the ones from aromatic polyimides yielded the best separation and mechanical properties. The polymers tested by Jones and Koros were cellulose acetate, polyaramides, and polyimides. Polyfurfural alcohol was used by Foley and co-workers (Foley, 1995 Shiflett and Foley, 1999 Strano and Foley, 2002). A comparison of the O2 permeances and O2/N2 selectivities showed that the CMS membrane from polyimide was indeed much better than that from polyfurfural alcohol, as will be seen shortly. 

Polyimides (PI) exhibit very good chemical, mechanical and dielectric stability at temperatures from -150 to 250 C. These rigid polymers with a high glass transition temperature are mostly used in (micro)electronics, aircraft industry, space exploration and as polymeric separation membranes. Linear polyimides (LPI) are traditionally prepared by the two-step polymerization. The polyimideprecursor, polyamic acid (PAA) (the most often a solution in N-methyl-2-pyrrolidone), is prepared from an aromatic dianhydride and an aromatic diamine. This precursor is transformed into a polyimide using thermal or chemical imidization (Figure 2) [5]. 

Ekind E, Koytepe S Pajahan A, Segkin T (2006) Preparation and Characterization of an Aromatic Polyimide and Its Use as a Selective Membrane for H2O2. Turkish Journal Of Chemistry. 30 277-285. 

Chang KS, Tung CC, Wang KS, Tung KL (2009) Free Volume Analysis and Gas Transport Mechanisms of Aromatic Polyimide Membranes A Molecular Simulation Study). Phys. Chem. B. 113 9821-9830. 

Several materials have been studied on the goal of producing cost-effective PFMs [55-62]. Some of these are PBI-based membranes, polysterene membranes, sulfonated polyimide, cross-Unked poly(vinyl alcohol), and phosphobenzene, sulfonated poly(aryl ether ketone) —based manbranes. Sulfonation of aromatic thermoplastics such as polyether sulfone, polybenzimidazole, polyimides, and poly(ether ether ketone) makes them proton conductive suitable for fuel cell... 

Kim, I.C., Lee, K.H., Tak, T.M. (2003) S3mthesis and asymmetric nanoiiltration membrane performance of heterogeneously sulfonated aromatic polyimides. Jourrud of Applied Polymer Science, 89, 2483-2489. 

In one recent report, aromatic polyimide polymer membranes cross-linked at elevated temperatures (up to 450 °C) showed resistance to plasticization to at least up to 3000 kPa (450 psia) CO2. Achieving uniform high temperature cross-linking of polymers in commercial membrane manufacturing has its own challenges. Solution-based chemistry to cross- link membrane may be more commercially amenable than the high temperature thermal rearrangements. 

Relation of gas permeability with struction of aromatic polyimides II. J. Membr. Sci. Ill, 183. Hirayama, Y., Yoshinaga, T., Nakanishi, S., and Kusuki, Y. (1999). Relation between gas permeabilities and structure of polyimides. In B. D., Freeman and I. Pinnau (Eds.), Polymer Membranes for Gas and Vapor Separation. ACS Symposium Series 733. American Chemical Society Washington, DC, p. 194. 

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