Ketones, membranes cross-linked

The behavior of membranes cross-linked by veurious ketones was investigated in the same way. These membranes possess exceptionally good mechcuiical properties. Moderate values for flux cuid phenol retention were found (see table III). Since the object only was to ccm are different cross-linking reagents, no further attempt was made to improve the flux and the retention. 

Kim, J., Kim, D., Pendant-sulfonated poly(arylene ether ketone) (PAEK) membranes cross-linked with a proton conducting reagent for fuel cells, J. Membr. Sci., 2012, 405, 176-184. 

Figure 18 shows the temperature dependence of the proton conductivity of Nafion and one variety of a sulfonated poly(arylene ether ketone) (unpublished data from the laboratory of one of the authors). The transport properties of the two materials are typical for these classes of membrane materials, based on perfluorinated and hydrocarbon polymers. This is clear from a compilation of Do, Ch 20, and q data for a variety of membrane materials, including Dow membranes of different equivalent weights, Nafion/Si02 composites ° ° (including unpublished data from the laboratory of one of the authors), cross-linked poly ary lenes, and sulfonated poly-(phenoxyphosphazenes) (Figure 19). The data points all center around the curves for Nafion and S—PEK, indicating essentially universal transport behavior for the two classes of membrane materials (only for S—POP are the transport coefficients somewhat lower, suggesting a more reduced percolation in this particular material). This correlation is also true for the electro-osmotic drag coefficients 7 20 and Amcoh...

In reactions with polymer-bound catalysts, a mass-transfer limitation often results in slowing down the rate of the reaction. To avoid this disadvantage, homogenous organic-soluble polymers have been utilized as catalyst supports. Oxazaborolidine 5, supported on linear polystyrene, was used as a soluble immobilized catalyst for the hydroboration of aromatic ketones in THF to afford chiral alcohols with an ee of up to 99% [40]. The catalyst was separated from the products with a nanofiltration membrane and then was used repeatedly. The total turnover number of the catalyst reached as high as 560. An intramolecularly cross-linked polymer molecule (microgel) was also applicable as a soluble support [41]. 

Zhang N, Zhang G, Xu D, Zhao C, Ma W, Li H, Zhang Y, Xu S, Jiang H, Sun H, Na H (2011) Cross-linked membranes based on sulfonated poly (ether ether ketone) (SPEEK)/Nafion for direct methanol fuel cells (DMFCs). Int J Hydrogen Energ 36 11025-11033... 

Zhao C, Lin H, Na H (2010) Novel cross-linked sulfonated poly(arylraie ether ketone) membranes for direct methanol fuel cell. Int J Hydrogen Eneig 35 2176-2182... 

Zhang Y, Fei X, Zhang G, Li H, Shao K, Zhu J, Zhao C, Liu Z, Han M, Na H (2010) Preparation and properties of epoxy-based cross-linked sulfonated poly(arylene ether ketone) proton exchange membrane for direct methanol fuel cell applications, bit J Hydrogen Energ 35 6409-6417... 

The H2 plasma was used to prepare poly(ether ether ketone)-polyurethane membranes (Salerno et al. 2009) before ammonia plasma treatment. Such pretreatment cross-links and stabilizes the surface of the membrane before grafting of the A-groups, so that the hydrophobic recovery of the flnal surface is signiflcantly reduced. 

Cross-linked sulfonated poly (ether ether Ketone) Membrane... 

Fig. 11.10 Water uptake isotherms of various ionomers and sulfuric acid at 80 C. Dowex 50 is an ion-exchange resin made of 4% cross-linked polystyrene divinyl benzene BPSH 40 is a 2-mil 40% randomly sulfonated biphenol sulfone 700 EW PFSA is a 1-mil membrane with a structure similar to Nafion Nafion 112 is a 2-mil extruded membrane and, PAEK triblock is a 1-mil triblock polyaryl ether ketone with a sulfonated middle block (Reproduced from C.K. Mittelsteadt and H. Liu. [30] by permission from John Wiley Sons)...

S. D. Mikhailenko, K. Wang, S. Kaliaguine, P. Xing, G. P. Robertson, M. D. Guiver, Proton conducting membranes based on cross-linked sulfonated poly(ether ether ketone) (SPEEK). J. Memb. Sci. 233, 93-99 (2004). 

A new method for the preparation of PEMs is based on cross-linking and by thermally activated bridging of the polymer chains with polyatomic alcohols through condensation reaction with sulfonic acid functions. This was applied to sulfonated poly(ether ether ketone) (SPEEK) and some of the membranes exhibited conductivity higher than 2 x 10 S cm at room temperature. The SPEEK may potentially find applications as PEM materials for fuel cells. 

Figure 26 Electron micrographs, (a) Transmission electron microscopy of a thin film of poly(26d)-ib/oc/r-polyisoprene-i /oc/c-poly(26d) cast from methyl isobutyl ketone (MIBK) (b) scanning electron microscopy (SEM) of the surface of cross-linked microporous membrane (c) SEM of cross section of cross-linked microporous membrane.

Jang, I.-Y, Kweon, O.-H., Kim, K.-E., Hwang, G.-J., Moon, S.-B., Kang, A.-S., Covalently cross-linked sulfonated poly(ether ether ketone)/tungstophosphoric acid composite membranes for water electrolysis apphcation, J. Power Sources, 2008, 181, 127-134. 

Di Vona, M.L., Sgreccia, E., Licoccia, S., Alberti, G., Tortet, L., Knauth, R, Analysis of temperature-promoted and solvent-assisted cross-linking in sulfonated poly(ether ether ketone) (SPEEK) proton-conducting membranes, J. Phys. Chem. B, 2009, 113, 7505-7512. 

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