S-SEBS

The effects of equivalent weight (FW = g polymer/mol SO3H) and water content on diffusion coefficient, solubility, and permeability of oxygen for fully hydrated BAM, S-SEBS, ETFE- -PSSA, Nafion 117, and BPSH membranes have been studied. It has been found that the diffusion coefficients of all the studied membranes decrease with increasing EW, while the solubility correspondingly increases. These trends are the same as found in... 

Kim, Kim, and Jung measured proton conductivity and MeOH permeability for a series of S-SEBS membranes. Both proton conductivity and MeOH... 

Ratios of proton conductivity to MeOH permeability. A, for various S-SEBS membranes as afunc-tion of sulfonation degree. (From Kim, J. et al. 2002. journal of Membrane Science 207 129-137.)... 

For ETFE- -PSSA membranes with the same lEC, water uptake is higher than MeOH uptake of the membrane, but for Nation and S-SEBS membranes, MeOH uptake of membrane is always higher than water uptake. Chemical structure and morphology of membranes affect the solvent absorption. Nafion is considered to consist of ionic clusters that are separated from the polymer phase. For grafted polymers, heterogeneity exists to some extent due to the hydrophobic base polymer however, a regular clustered structure, as in the case of Nafion, has not been proposed for these materials. 

Analysis of S-SEBS by SAXS has revealed the presence of cylindrical morphologies for a degree of sulfonation of <34%. Interestingly, different morphologies can also be observed when membranes are cast from different solvents. Membranes (27 mol% degree of sulfonation) cast from THE form lamellar morphologies, as seen in Figure 3.27, while those cast from MeOH/ THE (tetrahydrofuran) (20/80 v/v) exhibit a diffusive phase boundary with disorderly interconnections between domains. This is due to the differences... 

Edmondson, C. A., Eontanella, J. J., Chung, S. H., Greenbaum, S. G. and Wnek, G. E. 2001. Complex impedance studies of S-SEBS block polymer proton-conducting membranes. Electrochimica Acta 46 1623-1628. 

Sebacic acid, bis -ethylhexyO ester. See Dioctyl sebacate Seback acid, dibulyl ester. See Dibutyl sebacate S-EB-S SEBS copolymer. See Styrene-ethylene/butylene-slyrene block copolymer... 

Synonyms Polystyrene-block-poly (ethylene-ran-butylene)-block-polysty-rene S-EB-S SEBS copolymer Classification Thermoplastic elastomer... 

Y. Araki, Y. Hori, K. Suzuki, H. Shirai, K. Kato, H. Saito, Flexible and flame-retardant S-SEB-S triblock copolymer/PPE nano-alloy, Journal of Applied Polymer Science 131 (13) (2014) 40446. 

Figure 6.9 (a) Ionic exchange capacity and (b) proton conductivity as a function of sulfonation time for s-SEBS-PVDF blend membranes with different compatibilizers. Reproduced with permission from... 

It is well accepted that the superior properties of Nafion membranes result from a phase separation between the hydrophobic perlluorinated polymer backbone and the sulfonic acid bearing side-chains. This phase separation leads to the formation of ion-conducting channels in the nm-range. Also ion-exchange membranes derived from sulfonated styrene-ethylene/butylene-styrene triblock copolymers (s-SEBS) exhibit a phase-separated morphology, which led to proton conductivities similar to Nafion but with a much lower methanol crossover [178]. 

C. A. Edmondson, J. J. Fontanella, Free volume and percolation in S-SEBS and fluorocarbon proton conducting membranes. Solid State Ionics 152-153 (2002) 355-361. 

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