TY - JOUR
T1 - Thermodynamic study on vesicle formation and adsorption of decyltrimethylammonium decyl sulfate
AU - Villeneuve, Masumi
AU - Kaneshina, Shoji
AU - Aratono, Makoto
N1 - Funding Information:
M.V. is grateful to Prof. Dr. H. Hoffmann of the University of Bayreuth for the opportunity to try different techniques for the characterization of the surfactant aggregates in his group and to Deutscher Akademischer Austausch-dienst for the stipendium of her stay there. M.V. would like to thank very much Ms. C. Thunig of the University of Bayreuth for taking the micrographs and help in the characterization. This work was partly supported by Hayashi Memorial Foundation for Female Natural Scientists and the Grant-in-Aid for Scientific research (B) from the Ministry of Education, Science, Sports and Culture of Japan (No. 10440210).
PY - 2001/7/1
Y1 - 2001/7/1
N2 - The surface tension of an aqueous solution of decyltrimethylammonium decyl sulfate (DeTADeS) was measured as a function of temperature T at various molalities m̂ under atmospheric pressure. DeTADeS has been found to form equilibrium multilamellar vesicles (MLV) spontaneously. The surface density, the entropies of adsorption, and the entropy of vesicle formation are evaluated. The mechanism of formation of equilibrium vesicles is investigated from the standpoint of thermodynamics and from the comparison of the results with those of the micelle-forming systems. From the relatively small change of the surface density Γ̂H on T at a given m̂, the adsorbed film is implied to be tightly packed due to the strong electrostatic attraction between the polar headgroups. The energy change associated with adsorption from the vesicular state per mole of surfactant ΔVHu is positive in the entire temperature range; thus, the curved bilayer in MLV is energetically more favorable than the planar adsorbed film. From the negative values of the entropy of vesicle formation ΔWVS, it is concluded that vesicle formation is driven by enthalpy whereas micelle formation is mostly entropy driven.
AB - The surface tension of an aqueous solution of decyltrimethylammonium decyl sulfate (DeTADeS) was measured as a function of temperature T at various molalities m̂ under atmospheric pressure. DeTADeS has been found to form equilibrium multilamellar vesicles (MLV) spontaneously. The surface density, the entropies of adsorption, and the entropy of vesicle formation are evaluated. The mechanism of formation of equilibrium vesicles is investigated from the standpoint of thermodynamics and from the comparison of the results with those of the micelle-forming systems. From the relatively small change of the surface density Γ̂H on T at a given m̂, the adsorbed film is implied to be tightly packed due to the strong electrostatic attraction between the polar headgroups. The energy change associated with adsorption from the vesicular state per mole of surfactant ΔVHu is positive in the entire temperature range; thus, the curved bilayer in MLV is energetically more favorable than the planar adsorbed film. From the negative values of the entropy of vesicle formation ΔWVS, it is concluded that vesicle formation is driven by enthalpy whereas micelle formation is mostly entropy driven.
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U2 - 10.1006/jcis.2001.7536
DO - 10.1006/jcis.2001.7536
M3 - Article
AN - SCOPUS:0035399653
SN - 0021-9797
VL - 239
SP - 254
EP - 263
JO - Journal of Colloid And Interface Science
JF - Journal of Colloid And Interface Science
IS - 1
ER -