Polyelectrolytes protonic conduction

Fang, J., Guo, X., Harada, S., Watari, T., Tanaka, K., Kita, H. and Okamoto, K. 2002. Novel sulfonated polyimides as polyelectrolytes for fuel cell applications. 1. Synthesis, proton conductivity, and water stability of polyimides from 4,4 -diaminophenyl ether-2,2 -disulfonic acid. Macromolecules 35 9022-9028. 

Title Polyarylene, Process for Producing the Same, Solid Polyelectrolyte, and Proton-Conductive Film... 

Linear arrays of protonatable or hydrogen bonded sites may allow the directed long range transfer of protons, thus functioning as proton-conducting channel, i.e., as proton wire. Relevant systems would be linear polyamines or polyphenolic condensed aromatic units [8.218], self-assembled hydrogen bonded heterocyclic ribbons such as 116 (see Section 9.4.4) or polyelectrolyte membranes [8.219] in which collective proton motion may take place and lead to proton conductivity. 

Kreuer K-D, Wohlfarth A, de Araujo CC, Fuchs A, Maier J. Single alkaline-ion (Li+, Na+) conductors by ion exchange of proton-conducting ionomers and polyelectrolytes. Chem-PhysChem. 2011 12(14) 2558-60. 

In polyelectrolyte gels the variation of pH or salt concentration (cs) causes a swelling or shrinkage. Therefore, in this case chemical energy is transformed to mechanical work (artificial muscles). An increase of cs (or a decrease of temperature) makes the gel shrink. Usually, the shrinking process occurs smoothly, but under certain conditions a tiny addition of salt leads to the collapse of the gel [iii, iv]. Hydration of macroions also plays an important role, e.g., in the case of proton-conductive polymers, such as -> Nafion, which are applied in -rfuel cells, -> chlor-alkali electrolysis, effluent treatment, etc. [v]. Polyelectrolytes have to be distinguished from the solid polymer electrolytes [vi] (- polymer electrolytes) inasmuch as the latter usually contain an undissociable polymer and dissolved small electrolytes. 

G. Zundel, Hydrate structures, intermolecular interactions and proton conducting mechanism in polyelectrolyte membranes - infrared results, J. Membr. Sci., 1982, 11, 249-274 C. Heitner-Wirguin, Infra-red spectra of perfluorinated cation-exchange membranes, Polym., 1979, 20, 371-374 L.Y. Levy, A. Jenard and H.D. Hurwitz, Infrared investigation of ionic hydration in ion-exchange membranes. Part 1. Alkaline salts of grafted polystyrene sulphonic acid membranes, J. Chem. Soc., Faraday Trans. 

Cui ZM, Li NW, Zhou XC, Liu CP, Liao JH, Zhang SB, Xing W (2007) Stuface modified Nafion membrane by casting proton-conducting polyelectrolyte complexes for direct methanol fuel cells. J Power Sources 173 162-165... 

Yibnaztiirk S, Deligdz H, Yihnazoglu M, Damyan H, Oksuzomer F, K09 SN, Durmu A, Gtirkaynak A (2010) Self-assembly of highly charged polyelectrolyte complexes with superior proton conductivity and methanol barrier properties for fuel cells. J Power Sources... 

So, the overall reaction in the fuel cell is the combination of hydrogen and oxygen to yield water and an electromotive potential. Because the oxidation product of the fuel is essentially H+, the polyelectrolyte membrane is also addressed as a proton conducting membrane or a proton exchange membrane [90]. 

Alexei R. Khokhlov s main research interests are polymer science, statistical physics of macromolecules, physical chemistry of polyelectrolytes and ionomers, microphase separation in polymer systems, polymer liquid crystals, polyelectrolyte responsive gels, topological restrictions in polymer systems, dynamics of concentrated polymer solutions and melts, coil-globule transitions, associating polymers, computer simulation of polymer systems, biomimetic polymers, and proton-conducting polymer membranes. 

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. 

The amount of polyelectrolyte binder used in CLs is not as large as that in membranes [18] however, the amount is important because it is closely related to CL performance, catalyst utilization, and MEA durability [23, 24]. In current PEMFCs, PFSA ionomers are employed in the CL as binders and in the proton conducting electrolyte to extend the formation of the electrochemical three-phase interface [3]. The latter is important for obtaining desirable catalyst utilization and, thus, high performance of MEA. Since the reactant must be transported through the proton conducting electrolyte before it arrives at the reaction sites to carry out reactions, the binder in the CL must be reactant-permeable to avoid reactant mass transport limitations [25]. The reactant-permeable property of the binder is... 

Galperin, D. Y., and Khokhlov, A. R. 2006. Mesoscopic morphology of proton-conducting polyelectrolyte membranes of Nafion type A self-consistent mean field simulation. Macromol. Theory Simul. 15(2), 137-146. 

Khiterer, M., Loy, D.A., Cornelius, C.J., Fujimoto, C.H., Small, J.H., Mclntire, T.M., and Shea, K.J. (2006) Hybrid polyelectrolyte materials for fuel cell applications design, synthesis, and evaluation of proton-conducting bridged polysilsesquioxanes. Chem. Mater., 18, 3665-3673. 

A membrane ionomer, in particular a polyelectrolyte with an inert backbone such as Nafion . These require a plasticizer (typically water) to achieve good conductivity levels and are associated primarily, in their proton-conducting form, with solid polymer-electrolyte fuel cells. 

Zygatfio-Monikowska E, Florjanczyk Z, Wielgus-Bany E, Pasniewski J (2006) Proton conducting gel polyelectrolytes based on 2-acrylamido-2-methyl-l-propanesulfonic add (AMPSA) copolymers with polyfunctional monomers Part I. Anhydrous systems. J Power Sources 159(1) 385-391, http //dx.doi.Org/10.1016/j.jpowsour.2006.02.036... 

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