ISSN:
1572-8927
Keywords:
Volume, apparent molar
;
heat capacity, apparent molar
;
micellization
;
mixed micelle
;
alcohol
;
urea
;
surfactant
;
octylammonium bromide
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The densities and volumetric heat capacities of urea and alcohols were measured in aqueous solutions of octylammonium bromide (OABr) and of OABr in aqueous urea and alcohol solutions. The alcohols studies were methanol, ethanol, 1-propanol, 2-propanol, n-butanol, t-butanol, n-pentanol, n-hexanol and 2-butoxyethanol (BE). In most experiments, the concentration of the reference solute was kept low, and volumes and heat capacities of transfer from water to the mixed solvent were calculated. A more complete study was made with the system BE-OABr-H2O where both solutes were systematically changed. The observed trends in the thermodynamic functions can be explained through three effects: interactions between the reference solute and the cosolvent in the premiceller region of the surfactant or pre-aggregation region of the alcohol, a distribution of the reference solute between water and the micelle or microphase and an equilibrium displacement of the system, monomer-aggregate, in the vicinity of the reference solute.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00646395
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