Protonation degree

The dependence of the protonation degree on the neutralization degree has been determined for various acids from spectroscopic and conductivity measurements 75). It was found that the protonation behaviour is only slightly dependent on the nature of the counterions, and on the nature of the macromoiecular chain (the isotactic polymers are less protonated, but the difference is very small) while a large amount... 

There have been a number of calculations recently on the vibrations of H5OJ beyond the harmonic approximation. As noted already, such calculations are essential due to the highly anharmonic nature of these vibrations. Attempts to go beyond the harmonic approximation have been done in reduced dimensionality [27, 56] and also with the additional vibrational adiabatic approximation [56], These calculations selected the three proton degrees of freedom and the OO-stretch as the reduced dimensionality space. While such approaches are better in... 

PolyanUine (PANI) and its derivates represent a very important class of conducting polymers, in which the electronic structure can be modulated by changing the oxidation and/or protonation levels [5]. The half-oxidized forms of PANI have more environmental stability than the others, and can be changed from the semiconductor state (called the emeraldine base, PANI-EB, see Scheme 8.2 for y = 0.5), to the highly conducting form (called the emeraldine salt, PANI-ES, see Scheme 8.1) just by changing the protonation degree of the polymeric backbone [5]. 

The micellization of a similar system, namely PHEGMA-PDEAEMA, upon changes in the protonation degree of the amine containing block has been studied in detail by light scattering and NMR [60]. The above polymer was molecularly dissolved when the degree of... 

In the binary systems, 100-AMP formation of [H (IOO) (AMP)] )+ species with protonation degrees varying from = 3 to = 8 were observed. On the other hand, 100 forms Cu + complexes of 1 1 and 2 1 stoichiometry. The insertion of all these data, together with the protonation constants of polyamine and AMP and the formation constants of Cu " -AMP as known parameters in the titrations... 

Membranes were prepared using dry Nafion powder [31] that was obtained by evaporating the solvent from a commercial Nafion solution. The powder was equilibrated in an aqneous NaCl/HCl solution with a preset NaVH " concentration ratio to adjust the protonation degree of the Nafion polymer. The snbstitnted Nafion was dried again and then mixed with an appropriate amount of PBI in DMAc solvent. Membranes were solution cast into a glass dish. After solvent evaporation at 80°C, the films were annealed at 150°C for 3 h. The resultant membranes (50-100 pm in dry thickness) were conditioned by boiling in IM H SO followed by extensive washings with de-ionized water. Membranes were stored at room temperatnre in water for later use. 

Fig. 14.16 Membrane proton conductivity of PBI-doped Nafion membranes (in water at 25°C) as a function of the Nafion powder protonation degree and PBI content. (Reprinted from [31], with permission from Elsevier.)...

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