Change of water structure by solvents and polymers

Viscosity measurements have been made of water-solvent and water-polymer solutions in a temperature range of 20–60 centigrades. A medium structure temperatureT ₀ was calculated from the Vogel-equation. Water has a structure temperature of 140–150 K, its decrease indicates structure breakage, an increase structure promotion. Pyridine, dioxane, dimethylformamide and urea are structure breakers. This is explained by a shift of the equilibrium — bonded water molecules — nonbonded — to the right. Acetone shows hydrophobic bonding in the same concentration range of 0–10 mole % as the normal alcohols. They are quasifree liquids-structure temperature zero-in the pure state. This is explained by hydrogen bridged dimer formation with the exception of tert-butanol. Its 3 methylgroups sterically prevent dimer formation and cause structuring. Adding urea to methanol-water solutions breaks water structure according to urea concentration but extends the hydrophobic bonding maximum over the whole diagram. Glucose-water solutions have a minimum in the structure temperature diagram. Its left side indicates waterstructure breakage, its right side formation of a new structure forced upon water by the sugar. The equilibrium can be formulated: Waterlike bonded-nonbonded-hetero (solvent)-like bonded, Ribose also shows this minimum but after a short range of heterobondedness the structure is completely broken to nonbondedness.The polymers dextrane and polyvinylpyrrolidone are strong waterstructure breakers. Dextrane much stronger than PVP, it breaks to nonbondedness while PVP maintains a certain structuring, perhaps indicating heterobonding at higher concentrations. Polyacrylamide is a strong structurebreaker. It resembles urea in this sense. Perhaps the solvationwater structure of the NH₂ groups is very different from pure waterstructure. Polyacrylicacid breaks waterstructure completely, if sodiumchloride is added waterstructure is rebuilt again. The only waterstructure promoting polymer is natural gelatine. Perhaps this structure is different from pure water or the watermolecule equilibrium is shifted towards bondedness. The structure temperatures of pure polyethyleneglycoles show a minimum with increasing molecular weight. The high structure temperature of the small chains is explained by long chain assoziates formation through hydrogen bridging. This liquid of long assoziate chains is structured and has a high structure temperature. With increasing molecular weight ringformation instead of linear assoziation becomes possible. These neutral rings form a free liquid. Long chains again have a linear structure and the structure temperature increases at higher molecular weights. Existence of linear chain assoziation of low molecular PEGs is proved with their breakage by adding the chain terminating methanol.Dedicated to Prof. Dr. F. H. Müller.Herrn Chemotechniker D. Ziegler möchte ich für die sorgfältige Durchführung der Messungen sehr danken.Dem Verband der Chemischen Industrie danke ich sehr für die Ermöglichung der Arbeit.