Polyimide membranes polyimides

A second form of desolvation chamber relies on diffusion of small vapor molecules through pores in a Teflon membrane in preference to the much larger droplets (molecular agglomerations), which are held back. These devices have proved popular with thermospray and ultrasonic nebulizers, both of which produce large quantities of solvent and droplets in a short space of time. Bundles of heated hollow polyimide or Naflon fibers have been introduced as short, high-surface-area membranes for efficient desolvation. 

Miscellaneous Applications. Ben2otrifluoride derivatives have been incorporated into polymers for different appHcations. 2,4-Dichloroben2otrifluoride or 2,3,5,6-tetrafluoroben2otrifluoride [651-80-9] have been condensed with bisphenol A [80-05-7] to give ben2otrifluoride aryl ether semipermeable gas membranes (336,337). 3,5-Diaminoben2otrifluoride [368-53-6] and aromatic dianhydrides form polyimide resins for high temperature composites (qv) and adhesives (qv), as well as in the electronics industry (338,339). 

Membrane modules have found extensive commercial appHcation in areas where medium purity hydrogen is required, as in ammonia purge streams (191). The first polymer membrane system was developed by Du Pont in the early 1970s. The membranes are typically made of aromatic polyaramide, polyimide, polysulfone, and cellulose acetate supported as spiral-wound hoUow-ftber modules (see Hollow-FIBERMEMBRANEs). 

Newer fabrics, not in common use but in development, test, and field trials, are described for higher temperature applications by Reference [50]. Application to 400°F—2100°F are potentially available using ceramic fibers Nextel 312 , laminated membrane of expanded PTFE on a substrate, polyimid fiber P-84, Ryton polyphenylene sulfide, and woven fiberglass. The heat and acid resistance of these new materials... 

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. 

Okamoto, K.,S. Kawamura, M. Yoshino, H. Kita, Y. Hirayama, N. Tanihara, and Y. Kusuki, Olefin/ paraffin separation through carbonized membranes derived from an asymmetric polyimide hollow fiber membrane, Ind. Eng. Chem. Res., 38, 4424,1999. 

In 1977, Parshall and co-workers published their work on the separation of various homogeneous catalysts from reaction mixtures.[46] Homemade polyimide membranes, formed from a solution of polyamic acid were used. After reaction the mixture was subjected to reverse osmosis. Depending on the metal complex and the applied pressure, the permeate contained 4-40% of the original amount of metal. This publication was the beginning of research on unmodified or non-dendritic catalysts separated by commercial and homemade membranes. 

Another concern for polystyrene- and some aromatic-based PEMs is hydrolysis of fhe sulfonic acid group from aromatic rings as well as hydrolytic cleavage of polymer backbone under fuel cell conditions for aromafic polymers including polyimides, poly(arylene ethers), poly(ether ketones), and poly(ether sulfones). It is well known that the sulfonation of aromafic rings is a reversible process especially at low pH and at elevated temperature (Scheme 3.3). The reversibility of sulfonation, for example, is used in fhe preparafion of trinitrotoluene or picric acid. Por the simplest membrane of the class of arylsulfonic acids (i.e., benzenesulfonic acid), fhe reacfion occurs upon freatment with a stream of superheated steam at 180°C.i ... 

Zhou, H., Miyatake, K. and Watanabe, M. 2005. Polyimide electrolyte membranes having fluorenyl and sulfopropoxy groups for high-temperature PEFCs. Fuel Cells 5 296-301. 

Genies, G., Mercier, R., Sillion, B., Gomet, N., Gebel, G. and Pineri, M. 2001. Soluble sulfonated naphthalenic polyimides as materials for proton exchange membranes. Polymer 42 359-373. 

Okamoto, K. 2003. Sulfonated polyimides for polymer electrolyte membrane fuel cell. Journal of Photopolymer Science and Technolgy 16 247-254. 

Faure, S., Pineri, M., Aldebert, R, Mercier, R. and Sillion, S. 1999. Sulfonated polyimides, membranes and fuel cells. E. Patent 897 407 Al. 

Zhou, W, Watari, T., Kita, H. and Okamoto, K. 2002. Gas permeation properties of flexible pyrolytic membranes from sulfonated polyimides. Chemistry Letters 5 534-535. 

Shobha, H. K., Sankarapandian, M., Glass, T. E. and McGrath, J. E. 2000. Sulfonated aromatic diamines as precursors for polyimides for proton exchange membranes. Abstracts of Papers of the Americttn Chemical Society 220 11278-11278. 

Einsla, B. R., Hong, Y. T., Kim, Y. S., Wang, F., Gunduz, N. and McGrath, J. E. 2004. Sulfonated naphthalene dianhydride based polyimide copolymers for proton-exchange-membrane fuel cells. 1. Monomer and copolymer synthesis. Journal of Polymer Science Part A Polymer Chemistry 42 862-874. 

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. 

Glassy polymers with much higher glass transition temperatures and more rigid polymer chains than rubbery polymers have been extensively used as the continuous polymer matrices in the zeolite/polymer mixed-matrix membranes. Typical glassy polymers in the mixed-matrix membranes include cellulose acetate, polysul-fone, polyethersulfone, polyimides, polyetherimides, polyvinyl alcohol, Nafion , poly(4-methyl-2-pentyne), etc. 

Zeolite/polymer mixed-matrix membranes prepared from crosslinked polymers and surface-modified zeolite particles offered both outstanding separation properties and swelling resistance for some gas and vapor separations such as purification of natural gas. Hillock and coworkers reported that crosslinked mixed-matrix membranes prepared from modified SSZ-13 zeolite and 1,3-propane diol crosslinked polyimide (6FDA-DAM-DABA) synthesized from 2,2 -feis-(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, p-dimethylaminobenzylamine-and 3,5-diaminobenzoic acid displayed high CO2/CH4 selectivities of up to 47 Barrer and CO2 permeabilities of up to 89 Barrer under mixed gas testing conditions [71]. Additionally, these crosslinked mixed-matrix membranes were resistant to CO2 plasticization up to 450 psia (3100kPa). 

Kulkami, S. and Hasse, D.J. (2007) Novel polyimide based mixed matrix composite membranes. US Patent Application 2007/0199445 Al. 

Pechar, T.W., Tspatsis, M., Marand, E., and Davis, R. (2002) Preparation and characterization of a glassy fluorinated polyimide zeolite mixed matrix membrane. Desalination, 146, 3-9. 

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