Proton conductivity acid-base

A number of proton-conducting acid-base solid composites were made by Yamada et such as from the... 

Fig. 5.22 Proton-conducting membrane based on benzyl sulphonic acid siloxane.

Protonation by acid-base chemistry leads to an internal redox reaction (Fig. 11.19), without change of the number of electrons (Heeger, 2001 MacDiarmic, 2001). The semiconductor (emeraldine base, emeraldine salt, 100 S/cm). Complete protonation of the imine nitrogen atoms in emeraldine base by aqueous HC1 results in the formation of a delocalised polysemiquinone radical cation. This is accompanied by an increase in conductivity of more than 12 orders of magnitude. 

Asensio JA, Borr6s S, G6mez-Romero P (2004) Proton-conducting membranes based on poly (2,5-benzimidazole) (ABPBI) and phosphoric acid prepared by direct acid casting. J Membr Sci 241 89-93... 

Namazi H, Ahmadi H (2011) Novel proton conducting membranes based on butylsulfonated poly [2,2 -(/n-pyrazolidene)-5,5 -bibenzimidazole] (BS-PPBI) proton conductivity, acid doping and water uptake properties. J Membr Sci 383 280-288... 

Staiti P (2001) Proton conductive membranes based on silicotnngstic acid/silica and polybtmzrmidazole. Mater Lett 47 241-246... 

The acid in the catalyst layer is retained by capiUaiy forces and by the hydrophobicity of the microporous layer while the acid in the membrane is held by the acid-base interaction as well as physical absorption. A recent study showed that a stable interface between the membrane and the catalyst layer can be sustained as long as the proton conducting acid phase is established. Electrodes with no polymeric binder were constructed with improved performance and good stability [48]. 

At present, in almost all work on fuel cells of the PEMFC and DMFC type, Nafion-type proton-conducting membranes based on perfluorinated sulfonic acids (PFSAs) have been used (Figure 13.1). Some properties of these membranes had been reported in Section 3.1.1. They have a high chemical stability and fully adequate protonic conductivity. Fuel cells built with such membranes offer rather good performance and relatively long life. It is not an exaggeration to say that the broad development of fuel cells and the general interest displayed in fuel cells today would have been impossible without the development and availability of these membranes. 

Stadny, I. A., Konovalova, V. V, and Yevdokymenko, V. O. et al. Proton conductive membranes based on polyvinyl alcohol and polystyrenesulfonic acid. Chemical sciences, Magisterium, 33, 38 (2008). 

Li, H.T., Wu, J., Zhao, C.J., Zhang, G., Zhang, Y., Shao, K., Xn, D., Lin, H.D., Han, M.M., Na, H., Proton-conducting membranes based on benzimidazole containing snlfo-nated poly(ether ether ketone) compared with their carboxyl acid form, Int. J. Hydrogen Energy, 2009, 34, 8622-8629. 

Acid—Base Chemistry. Acetic acid dissociates in water, pK = 4.76 at 25°C. It is a mild acid which can be used for analysis of bases too weak to detect in water (26). It readily neutralizes the ordinary hydroxides of the alkaU metals and the alkaline earths to form the corresponding acetates. When the cmde material pyroligneous acid is neutralized with limestone or magnesia the commercial acetate of lime or acetate of magnesia is obtained (7). Acetic acid accepts protons only from the strongest acids such as nitric acid and sulfuric acid. Other acids exhibit very powerful, superacid properties in acetic acid solutions and are thus useful catalysts for esterifications of olefins and alcohols (27). Nitrations conducted in acetic acid solvent are effected because of the formation of the nitronium ion, NO Hexamethylenetetramine [100-97-0] may be nitrated in acetic acid solvent to yield the explosive cycl o trim ethyl en etrin itram in e [121 -82-4] also known as cyclonit or RDX. 

For cryptands in which the molecular cavity is larger than in the case of the [l.l.l]-species [78], proton transfer in and out of the cavity can be observed more conveniently. Proton transfer from the inside-monoprotonated cryptands [2.1.1] [79], [2.2.1] [80], and [2.2.2] [81 ] to hydroxide ion in aqueous solution has been studied by the pressure-jump technique, using the conductance change accompanying the shift in equilibrium position after a pressure jump to follow the reaction (Cox et al., 1978). The temperature-jump technique has also been used to study the reactions. If an equilibrium, such as that given in equation (80), can be coupled with the faster acid-base equilibrium of an indicator, then proton transfer from the proton cryptate to hydroxide ion... 

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