Estimation of excess solvation numbers of water and cosolvents from preferential interaction and volumetric experiments

2004 ◽  
Vol 120 (10) ◽  
pp. 4989-4990 ◽  
Author(s):  
Seishi Shimizu
Keyword(s):  
Preferential Interaction ◽  
Solvation Numbers

Studies of Polymer Solvation by Dielectric Relaxation Spectroscopy IV:Polyvinylpyrrolidone in Urea Derivatives at Different Temperatures

1991 ◽  
Vol 46 (11) ◽  
pp. 1001-1008 ◽  
Author(s):  
M. Rohmann ◽  
M. Stockhausen
Keyword(s):  
Activation Enthalpy ◽  
Repeat Unit ◽  
Dielectric Spectrum ◽  
Type Ii ◽  
Polymer Content ◽  
Dielectric Relaxation Spectroscopy ◽  
Urea Derivatives ◽  
Solvation Numbers ◽  
Different Temperatures ◽  
Repeat Unit Of Polymer

AbstractThe dielectric spectrum is measured up to 72 GHz of solutions of polyvinylpyrrolidone (PVP) in tetramethylurea (TMU), dimethylethylene urea and dimethylpropylene urea. Concentrations are up to a monomole fraction of 0.65 (PVP 1200) or 0.5 (PVP 40 000). Measuring temperatures are 20CC for all systems and additionally 40 and 60°C for the TMU solutions. For the description of the results a superposition of Debye type components is used, which are discussed in particular with respect to the solvent contributions. These can be distinguished into three regions: (i) Unaffected bulk-type; (ii) loosely affected, relaxation time and activation enthalpy increasing with increasing polymer content; (iii) quasi bound and moving together with the polymer. The solvation numbers (total of affected solvent per repeat unit of polymer) are about 1.5 to 2.

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