Das viskositätsverhalten von linearen und einfach gewinkelten Oligophenylene. 11. Mitteilung¹

Abstract

ZUSAMMENFASSUNG:Ziel dieser Arbeit sind Untersuchungen der Losungsviskositat von Verbindungen mit definierter Molekiilgestalt. Das Verhalten von methyl-und methoxylsubstituierten p-oligophenylenen sowie von methylsubstituierten, einfach gewinkelten Oligophenylenen wurde studiert.Eine Apparatur, die zur Erfassung geringer Viskositatsunterschiede geeignet ist, wird beschrieben. Die Temperaturkonstanz konnte mittels eines neuartigen Priizisions-Kontaktthermometers mit veranderlichem Regelbereich verbessert werden.Bei allen untersuchten Verbindungen zeigen die -qsp /c-Werte eine lineare Abhangigkeit von der Konzentration c. Anch bei den Verbindungen mit definierter Molekiilgestalt ergibt sich ein starker LosungsmitteleinfluR auf die Viskositat. In allen Losungsmitteln erhalt man eine lineare Viskositats-Molekulargewichtsbeziehnng. Die Befunde werden mit den Ergebnissen verglichen, die an Losungen knauelbarer Molekiile definierter GroRe erhalten wurden.Der EinfluQ der Molekiilform auf die Viskositat wird an einfach gewinkelten Oligophenylenen definierter Molekiilgestalt gezeigt. SUMMARY:The purpose of this work was the study of the viscosity in solution of substances with a defined molecular structure. The behaviour of methyl-und methoxyl substituted oligophenylenes with one angle were investigated.An apparatus suited for the measurement of minor differences in viscosity is described. The constancy of temperature was improved by a new precision contact thermometer with a variable adjustable temperature range.All substances which were examined showed a linear dependence of the -qsp/c-values from the concentration c. Also, in the case of substances with a defined molecular structure the solvent has a considerable influence on the viscosity. I n all solvents, a linear viscositymolecular weight dependence was obtained. The results were compared with those which had been obtained in solutions of molecules of a defined size and which could exist in a coiled form.The influence of the molecular form on the viscosity is demonstrated by oligophenylenes with one angle and a defined molecular structure.

Suzuki Polycondensation: Polyarylenes à la Carte

“…Additionally their solubility decreased dramatically with increasing chain length. [8,13] It is important to mention that H. O. Wirth already at that time had tried to overcome the problem of insolubility by attaching methyl-or methoxyl-substituents to the phenylene rings. However, the effect imparted by these substituents was not large enough to result in any sizeable solubility beyond the level of octamers.…”

“…They aimed for the synthesis of a series of oligomers with defined length and unique end groups including representatives with kinks in the trajectories caused by ortho and meta units. [6][7][8] The objective of these studies was to obtain intrinsically stiff oligomers and to investigate their solution viscosity. [8] A motivation for this effort was that at the time of their work it had been widely accepted that the original notion put forward by Staudinger [9] was in error.…”

“…[6][7][8] The objective of these studies was to obtain intrinsically stiff oligomers and to investigate their solution viscosity. [8] A motivation for this effort was that at the time of their work it had been widely accepted that the original notion put forward by Staudinger [9] was in error. He had proposed that linear chain macromolecules are more or less rod-like and should exhibit a correlation between intrinsic viscosity h i and molecular weight as h i ¼ KM a with a ¼ 1.0.…”

Rubredoxin reductase from Alcanivorax borkumensis: Expression and characterization

“…It was extensively explored by H. O. Wirth, W. Kern, and coworkers in Mainz already around 1960. They aimed for the synthesis of a series of oligomers with defined length and unique end groups including representatives with kinks in the trajectories caused by ortho and meta units 6–8. The objective of these studies was to obtain intrinsically stiff oligomers and to investigate their solution viscosity 8.…”

“…They aimed for the synthesis of a series of oligomers with defined length and unique end groups including representatives with kinks in the trajectories caused by ortho and meta units 6–8. The objective of these studies was to obtain intrinsically stiff oligomers and to investigate their solution viscosity 8. A motivation for this effort was that at the time of their work it had been widely accepted that the original notion put forward by Staudinger9 was in error.…”