Micelle and solvent relaxation in aqueous sodium dodecylsulfate solutions

被引:52
作者
Fernandez, P [1 ]
Schrödle, S [1 ]
Buchner, R [1 ]
Kunz, W [1 ]
机构
[1] Univ Regensburg, Inst Phys & Theoret Chem, D-93040 Regensburg, Germany
关键词
aggregation; dielectric relaxation; hydration; micelles; molecular dynamics;
D O I
10.1002/cphc.200300725
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Dielectric spectra have been measured for aqueous sodium dodecylsulfate (SDS) solutions up to 0.1 molL(-1) at 25degreesC over the frequency range 0.005 less than or equal to nu GHz(-1) less than or equal to 89. The spectra exhibit two relaxation processes at approximately 0.03 GHz and 0.2 GHz associated with the presence of micelles in addition to the dominant solvent relaxation process at approximately 18 GHz and a small contribution at approximately 1.8 GHz due to H2O molecules hydrating the micelles. Detailed analysis reveals that the micelles bind 20 water molecules per SDS unit, but not as strongly as trimethylalkylammonium halide surfactants do. The relaxation times and amplitudes of both micelle relaxation processes can be simultaneously analysed with the theory of Grosse, yielding the effective volume of a SDS unit in the micelle and the lateral diffusion coefficent of the bound counterions. The findings of this investigation fully corroborate recent molecular dynamics simulations on structure and dynamics of SDS micelles.
引用
收藏
页码:1065 / 1072
页数:8
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