Bestimmung wasserlöslicher Polyelektrolyte in Polyurethan-Dispersionen

Zusammenfassung Die Bestimmung wasserlöslicher Polyelektrolyte, die bei der Synthese segmentierter Polyurethanionomerer entstehen, erfolgte durch konduktometrische und potentiometrische Titrationsverfahren nach Abtrennung des Serums durch Ultrazentrifugieren oder Ausfrieren des Polymeren bzw. Abtrennung der wasserlöslichen Elektrolyte mit einem gemischten Ionenaustauscher. Diese Elektrolyte enthielten abhängig von der Rezeptur zwischen 25 und 72% der vorgegebenen Ionenkonzentration. Unterstellt man glatte, kugelförmige Latexpartikeln, so beträgt die Fläche pro festhaftende ionische Gruppe nur 60–170 Ų, wodurch eine erhebliche gegenseitige Beeinflussung der Ionen resultiert.Herrn Prof. Dr. Ing. Dr. h.c. mult. H. Zahn zum 65. Geburtstag gewidtmet (O. L.).     

Mixed complex combinations of Pd(II) with α-amino acids

Journal of Thermal Analysis and Calorimetry - The present work deals with the synthesis of eight mixed complex combinations of Pd(II) with different α-amino acids. In order to prove the...     

Iodine fluorosulfate reactions with fluorocarbons

Iodine monofluorosulfate has been found to react with fluoroolefins in the absence of a solvent to give the corresponding iodo alkyl fluorosulfates by addition of ?l and ?OSO₂F across the double bond. The observed products were ICF₂CF₂SO₃F, CF₃CFlCF₂SO₃F, and the isomer mixture ICF₂CFClSO₃F and ICFClCF₂SO₃F. Perfluorocyclobutene was unreactive. The iodine fluorosulfate used for this study was synthesized from the reactions of either I₂ or R_fI with ClSO₃F, with both reactions being new routes to this compound. These iodo fluorocarbon fluorosulfates are novel compounds and were characterized by spectroscopy and by formation of the derivatives CF₃CFICFO and ICF₂CFO.     

Influencing parameters in time resolved picosecond spectroscopy and a new light gate method

We show that the open period of a CS₂ light gate, triggered by a picosecond optical pulse, depends on the optical pathlength through the CS₂. An alternative to the light gate is suggested for time resolved spectroscopy. The working principle is based on scattering induced in CS₂. We have found that the broadband emission from H₂O or D₂O excited by a 5300 Å picosecond pulse is also of picosecond duration, but the blue part is delayed with respect to the red. From this delay time the lifetime of the ground state vibrational levels may be measured directly.     

Reaction of onium salts with nucleophilic reagents

Russian Chemical Bulletin -