Sulfonate ionic-phase

Fig. 7. A schematic view of Nafion membrane showing the microheterogeneous environment. A hydrophobic fluorocarbon phase B hydrophilic sulfonate ionic clusters C interfacial region formed between A and B and Ru adsorbed ruthenium complex water oxidation catalyst...

Tn the case of nonpolar diluents, very few studies have appeared in the literature. The Zn sulfonated polystyrene plasticized by 3.4 wt. % dodecane shows no change in either position, intensity or shape of the ionomer peak compared to that of the bulk polymer (27) this was taken to indicate that the ionic microphase is unaffected by this diluent. The Mn sulfonated polystyrene plasticized b,v up to 10 wt % DOP (Figure 11) shows a decrease in intensity of the peak, but no change in its shape or position (28). This was explained as a dilution effect of the ionic phase due to swelling of the matrix by the plasticizer. 

The dynamic mechanical and DSC results for sulfonated PP s combine to give strong evidence for the existence of ionic clusters in these materials. In addition they suggest that these clusters are only present above a critical sulfonate concentration of 10 mol %. These conclusions are based on the existence of an ionic-phase a relaxation for materials sulfonated above 10% and the deviation of the Tg vs. % sulfonation plot from typical copolymer-type behavior at this same concentration. 

The dynamic mechanical results of this study demonstrate that backbone crystallinity plays an important role in the properties of these materials. Moreover, it is observed that thermal history affects the properties of the materials investigated in a more complex manner than can be explained by simple changes in the degree of crystallinity. At low levels of sulfonation the materials generally behave very much like linear polyethylene, but this behavior is modified significantly as the level of sulfonation is increased. Evidence is clearly present for the existence of an ionic-phase relaxation that supports the proposed model for micro-phase-separated domains (5,6,7). However, owing to the effects of crystallinity the concentration at which the ionic-phase relaxation first... 

From Figure 10 it appears that a dipolar relaxation labeled a is superimposed on the phenomenon we have just discussed. The behavior of this a peak correlates well with the behavior of the dynamic mechanical a relaxation since it increases in magnitude and decreases in temperature with increasing sulfonation. The presence of this peak in the dielectric spectra of these materials and its behavior as a function of sulfonate concentration are consistent with the assignment of the mechanical a relaxation to an ionic-phase mechanism. However, it is not possible to cite this dielectric peak as proof of the mechanical assignment the known presence of ionic impurities in these systems and the unknown origin of the large increases in tan 8 and c dictate that the dielectric results be interpreted with caution. 

The general structure of Nafion in particular, and ionomers in general, as a function of water content has been the source of many studies as recently reviewed by Mauritz and Moore [21] and Kreuer et al. [10] For the most part, the experimental data have shown that a hydrated membrane phase separates into ionic and matrix or nonionic phases. The ionic phase is associated with the hydrated sulfonic acid groups and the matrix phase with the polymer backbone. Thus, water is associated with the hydrophilic ionic phase and not the hydrophobic matrix phase. The actual way in which the phases segregate within the polymer depends on the water content. 

When water-miscible ionic liquids are used as solvents, and when the products are partly or totally soluble in these ionic liquids, the addition of polar solvents, such as water, in a separation step after the reaction can make the ionic liquid more hydrophilic and facilitate the separation of the products from the ionic liquid/water mixture (Table 5.3-2, case e). This concept has been developed by Union Carbide for the hydroformylation of higher alkenes catalyzed by Rh-sulfonated phosphine ligand in the N-methylpyrrolidone (NMP)/water system. Thanks to the presence of NMP, the reaction is performed in one homogeneous phase. After the reaction. 

Electrospray has been successful for numerous azo dyes that are not ionic salts. Several anthraquinone dyes have been analysed by LC-ESI-MS [552]. Electrospray achieves the best sensitivity for compounds that are precharged in solution (e.g. ionic species or compounds that can be (de)protonated by pH adjustment). Consequently, LC-ESI-MS has focused on ionic dyes such as sulfonated azo dyes which have eluded analysis by particle-beam or thermospray LC-MS [594,617,618]. Techniques like LC-PB-MS and GC-MS, based on gas-phase ionisation, are not suitable for nonvolatile components such as sulfonated azo dyes. LC-TSP-MS on... 

The interfacial tension behavior between a crude oil (as opposed to pure hydrocarbon) and an aqueous surfactant phase as a function of temperature has not been extensively studied. Burkowsky and Marx T181 observed interfacial tension minima at temperatures between 50 and 80°C for crude oils with some surfactant formulations, whereas interfacial tensions for other formulations were not affected by temperature changes. Handy et al. [191 observed little or no temperature dependence (25-180°C) for interfacial tensions between California crude and aqueous petroleum sulfonate surfactants at various NaCI concentrations. In contrast, for a pure hydrocarbon or mineral oil and the same surfactant systems, an abrupt decrease in interfacial tension was observed at temperatures in excess of 120°C 1 20]. Non ionic surfactants showed sharp minima of interfacial tension for crude... 

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