Proton-conducting gel polymer

Hashmi, S. S. A. 2014. Quasi-solid-state pseudocapacitors using proton-conducting gel polymer electrolyte and poly(3-methyl thiophenej-ruthenium oxide composite electrodes. Journal of Solid State Electrochemistry 18 465-475. 

Proton-conducting gel polymer electrolyte (GPE) based on poly(vinylidene fluoride)-hexafluoropropylene (PVdF-HPA) or polyimethyl methacrylate-heteropolyacid) (PMMA-HPA)... 

Proton-conducting gel polymer electrolyte (GPE) doped with 12-PWA... 

S.S. Sekhon, H.P. Singh, Proton conduction in polymer gel electrolytes containing chlo-roacetic acids. Solid State Ionics, 175 (2004) 545-548. 

Novel proton-conducting gels have been prepared by entrapping HPA solutions in polar aprotic solvents within the polymer matrix. ... 

For the preparation of proton-conducting polymers, aminoalkyl-substituted siloxanes made by sol-gel processing of (MeO)3Si(CH2)3NR2 [for example, NR2 = NH2, NH(CH2)2NH2, NH(CH2)2NH(CH2)2NH2] were doped with CF3SO3H129. 

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. 

As for pure phosphoric acid, the transport properties of PBI and phosphoric acid also depend on the water activity, this is on the degree of condensation (polyphosphate formation) and hydrolysis. There is even indication that these reactions do not necessarily lead to thermodynamic equilibrium, and hydrated orthophos-phoric acid may coexist with polyphosphates in heterogeneous gel-like microstructures [99]. There is not much known on the mechanism of proton transport in polymer adducts with polyphosphates and/or low hydrates of orthophosphoric acid. Whether the increased conductivity at high water activities is the result of the plasticizing effect of the water on the phosphate dynamics, thereby assisting proton transfer from one phosphate to the other, or whether the water is directly involved in the conduction mechanism has not been elucidated. 

When this lead dioxide was heated and dehydrated, its capacity declined abruptly. These results indicate that the electrochemical reaction of Pb02 reduction proceeds in the hydrated (gel) zones of the particles and it is these gel zones that determine the electrochemical activity of the lead dioxide [59]. The gel zones of Pb02 particles have both electron and proton conductivity due to the polymer chains of the lead dioxide structure [59]. 

Connections between hydrated polymer chains in gel zones, through (a) and (b) Sb into an integral system with electron and proton conductivity [38]. 

Wu et al. [106] prepared hybrid direct methanol fuel cell membranes by embedding organophosphorylated titania submicrospheres (OPTi) into a CS polymer matrix. The pristine monodispersed titania submicrospheres of controllable particle size are synthesized through a modified sol-gel method and then phosphorylated by amino trimethylene phosphonic acid (ATMP) via chemical adsorption. Compared to pure CS membrane, the hybrid membranes exhibit increased proton conductivity to an acceptable level of 0.01 S/cm for DMFC application and a reduced methanol permeability of 5 xlO cm /s at a 2 M methanol feed. 

In general, the ionic transport in linear or crosslinked swollen polymers containing a low molecular weight polar or ion-chelating additive mainly occurs in the solvent phase [118, 120]. This concept has been applied to develop proton conducting polymeric gel or hydrogel membranes [121-123] which reach conductivity values around 10 S cm at room temperature and are not destroyed or dissolved even at high humidity levels. 

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