Reversible temperature-induced transformations of poly(N-ethyl-4-vinylpyridinium) complexes with dodecyl sulfate in aqueous salt solutions

Supramolecular organization of complexes formed by poly(N-ethyl-4-vinylpyridinium bromide) and sodium dodecylsulfate in aqueous salt solutions was studied as a function of temperature and concentration of the complexes. It was shown that a decrease in temperature and/or concentration of complexes led to their reversible disaggregation into a molecularly dispersed (“unipolymer”) state. The ratio between the components in complex particles remained unchanged in this case. It was first found that phase separation in aqueous solutions of the complexes upon temperature elevation is accompanied by the precipitation of a nonstoichiometric complex.     

Über die Dispersität von Metallen in Trägerkatalysatoren. II. Röntgenkleinwinkeluntersuchungen an Platin- und Palladium-Tonerde-Katalysatoren

On the Dispersion of Metals in Supported Catalysts. II. Small Angle X-ray Investigation. on Platinum/Alumina and Palladium/Alumina Catalysts The metal dispersion in 0.5% Pd/A1₂O₃. 0.5°% Pt/Al₂O₃ abd 1.5% Pt/Al₂O₃ catalysts was investigated by small angle X-ray scattering, Using a Kratky camera the difference scattering curves catalyst-carrier were evaluated. The assumption was made that the scattering centres are globular and that there is no interparticular scattering. From the Guinier approximation the Guinier radii R_G of the metal particles were determined. With the Pd catalyst always positive difference scattering curves were found, whereas negative values were found with the Pt catalysts at a scattering angle greater than 0.022 rad. Therefore only for the sample with 0.5% Pd the Porod invariant \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm \tilde Q}$\end{document} and the Porod radius R_P could be determined. From R_G and R_P the parameters of a two- and of a one-parametric distribution were calculated. The results are in good agreement with data from wide angle X-ray diffraction measurements.