Poly membranes properties

The design of bioeompatible (blood compatible) potentiometric ion sensors was described in this chapter. Sensing membranes fabricated by crosslinked poly(dimethylsiloxane) (silicone rubber) and sol gel-derived materials are excellent for potentiometric ion sensors. Their sensor membrane properties are comparable to conventional plasticized-PVC membranes, and their thrombogenic properties are superior to the PVC-based membranes. Specifically, membranes modified chemically by neutral carriers and anion excluders are very promising, because the toxicity is alleviated drastically. The sensor properties are still excellent in spite of the chemical bonding of neutral carriers on membranes. 

E Pefferkorn, A Schmitt, R Varoqui. Helix-coil transition of poly(a,L-glutamic acid) at an interface Correlation with static and dynamic membrane properties. Biopolymers 21 1451-1463, 1982. 

The membrane properties of the microporous polypropylene/poly-acetylene structure were measured, and a comparison with the original properties is given in Table II. 

A. Jonqui6res, R. Cldment, and P. Lochon. New film-forming poly(ureth-ane-amide-imide) block copolymers influence of soft block on membrane properties for the purification of a fuel octane enhancer by pervaporation. Eur. Polym. J., 41(4) 783-795, April 2005. 

It is largely accepted that a high dietary intake of poly-unsaturated fatty adds (PUFA) in the a>-3 series has beneficial effects. Recently, cellular lipid metabolism has been suggested as a target for cancer therapy. Cancer cells, compared with normal cells, seem to be vulnerable to exposure of certain polyunsaturated fatty acids (PUFAs), especially those in the o -3 series. Characteristic for these compounds are their poor abihty to be oxidized in the cell due to multiple double bonds. They are however likely to be ester-rfied to oflier Upids, and their incorporation into membrane phosphohpids will influence membrane properties such as fluidity, protein interactions and susceptibility to lipid peroxidation. The hypohpidemic properties of some (0-3 fatty acids, such as EPA, are probably e lained by an induction of mitochondrial P -oxidation that is not found after adrninistration of the non-hypolipidemic (o-3 PUFA docosahexaenoic acid (DHA)." However, both eicosapentaenoic acid (EPA) and DHA cause increased peroxisomal... 

The importance of the choice of casting solvent on membrane properties is also evident in studies of proton conductivity of sulfonated poly-styrene-foZock-(ethylene-co-butylene)-fc/ock-sulfonated polystyrene (SSEBS) (Scheme 2c) membranes prepared from different compositions of mixed casting solvents (MeOH/THF) (Fig. 25). For example, the conductivity of SSEBS membranes possessing a degree of sulfonation (DS) of 27 mol % increases with an increasing fraction of methanol in the solvent mixture. For membranes with a DS of 42 mol %, the proton conductivity increases with concentration of methanol fraction and levels off at higher volume fraction. 

The membrane surfaces have also been grafted or coated with polyacrylamide, poly(acrylic acid) [70, 71], poly(vinyl alcohol) and cellulose derivatives [72]. Another possibility for improving the membrane properties is the use of polymer blends. Blends of PVDF/PVP [73, 74], PVDF/poly(ethylene glycol) (PEG) [75], PVDF/sulfonated polystyrene [76], PVDF/poly(vinyl acetate) [77] and PVDF/ poly(methyl methacrylate) [78] have been used in the preparation of micropor-ous membranes. 

YA. Gallego, a. Mendes, LM. Madeira, S.P. Nunes, Proton electrolyte membrane properties and direct methanol fuel-cell performance I. Characterization of hybrid sulfonated poly-(ether ether ketone)/zirconium oxide membranes. Journal [Pg.85]

Yamada, K., Ebihara, T., Gondo, T., Sakasegawa, K. and Hirata, M. 1996. Membrane properties of porous and expanded poly(tetrafluoroethylene) films grafted with hydrophilic monomers and their permeation behavior. 

A.K. Mohanty, S. Banerjee, H. Komber, B. Voit, Imidoaryl biphenol based new fluorinated sulfonated poly(arylene ether sulfone) copolymers and their proton exchange membrane properties, Solid State Ionics 254 (2014) 82-91. 

W. Guo, X. Li, H. Wang, J. Pang, G. Wang, Z. Jiang, S. Zhang, Synthesis of branched sulfonated poly(aryl ether ketone) copolymers and their proton exchange membrane properties, J. Memb. Sci. 444 (2013) 259-267. 

Y. Chang, Y.B. Ixe, C. Bae, Partially fluorinated sulfonated poly(ether amide) fuel cell membranes influence of chemical structure on membrane properties. Polymer 3 (1) (2011) 222-235. 

T. Suda, K. Yamazaki, H. Kawakami, Syntheses of sulfonated star-hyperbranched poly-imides and their proton exchange membrane properties, J. Power Sources 195 (15) (2010) 4641-4646. 

Okuno, H., Renzo, K., Uragami, T, 1993. Influence of casting solution additive, degree of polymerization, and polymer concentration on poly(vinyl chloride) membrane-properties and performance. Journal of Membrane Science 83,199-209. 

Cornelius et al. have synthesized a series of unique poly(phenylene)-based polyelectrolytes by Diels-Alder polymerization followed by post-sulfonation (Fig. 7.12) [29-32]. The ionomers are composed of sulfonated, highly phenylated poly(phenylene)s and do not carry any heteroatoms as their constituents except for the sulfonic acid groups. The complete aryl backbone resulted in a tough rigid-rod material with no Tg below the decomposition temperature. The stiffness of the ionomer backbone did not negatively affect the membrane properties such as water uptake (21-137%, in water) and proton conductivity (13-123 mS/cm, in water at 30°C) with lECs ranging from 0.98 to 2.2 meq/g. 

Block copolymers combing PBI with other types of macromolecular units have also been developed for superior membrane properties, as shown in Fig. 7.6. Two types of copolymers have been prepared, characterized, and evaluated as fuel cell electrolytes. One is the sulfcmated copolymer containing PBI and snUrmated polymer moieties for low temperature PEMs in both PEM fuel cells and direct methanol fuel cells (DMFCs) [123-126]. The other is the random copolymer containing PBI and poly(imine/ amide) moieties [127, 128]. For the sulfonated PBI copolymers, benzimidazole monomers... 

Figures. Comparison of membrane properties of APG plasma treated poly(dimethylsiloxane) membrane with those of low pressure plasma treated poly(dimethylsiloxane) membranes and conventional polymer membranes. iSlled circles APG plasma treated membranes, filled triangles low pressure plasma treated membrane from (1), unfilled circles conventional polymer membrane data from (10,11). In all cases, a membrane thickness of 1 pm was used to calculate permeance, RcX)2> permeability data.

Dependence of the membrane properties from the type of sulfonated poly(etherketone). The three different sulfonated poly(elherketones) SPEK, SPEEK, and SPEKEKK have been used in covalently cross-Unked blend membranes as the H+-conductive component. It was found that the properties of the different membranes were very close to one another [87]. 

Dependence of the membrane properties from the type of sulfmated poly(ethersnlfone). The two different poly(ethersulfones), PSU and PPSU, were used as the cross-linking component in the covalently cross-linked blend membranes. The membranes prepared from these polymers showed comparable properties. There are some indications that the thermal and mechanical stability of the membranes from sulfmated PPSU is slightly better than the thermal and mechanical stability of membranes using sulfmated PSU [88]. 

Dependence of the membrane properties from membrane type (nonfluorinated and partially fluorinated ionomer). We have developed partially fluorinated covalently cross-linked membranes by reaction of disulfmated poly (ethersul-fones) with pentaflnorobenzene sulfochloride and different cross-hnkers [90]. The scheme for the preparation of such partially fluorinated covalent ionomer networks is given in Fig. 8.10. The obtained membranes showed high H -conductivities and moderate SW. In Table 8.5, some of the properties of one... 

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