142-87-0Relevant articles and documents
Counterion Effects on the Structure and Solubilization Properties of Anionic Detergents. Role of Hydrophobic Cations in Stabilizing Micelles and Attenuating Their Solvent Properties
Bonilha, Joao B. S.,Georgetto, Rose Mary Zumstein,Tedesco, Antonio Claudio,Miola, Laerte,Whitten, David G.
, p. 367 - 372 (1989)
A series of alkyl sulfate detergents has been investigated in the presence of the cations Na+, methylviologen(2+) (MV2+), 4-(cyanomethyl)pyridinium(+) (CMP+), and tetramethylammonium (TMA+).The binding of these ions to the aqueous micellar assemblies has been measured through studies of luminescence quenching with the extramicellar probe, RuL34-, where L=4,4'-dicarboxy-2,2'-bipyridine.A general comparison of the alkyl sulfate aggregates with the ''nonquenching cations'' Na+ and TMA+ shows that the latter ion reduces the critical micelle concentration but at the same time depresses the ability of the detergent assemblies to ''bind'' or solubilize the hydrophobic quencher cations MV2+ or CMP+.The reduced binding ability of the TMA+ aggregates compared to that of the corresponding Na+ soaps shows up largely in the form of a reduced favorable ΔSo for the solubilization in the case of the formed.The results are in accord with a picture of the TMA+ micelle as being more stable and more disordered than the corresponding assembly with Na+ as the counterion.
The association of an ionic surfactants with β-cyclodextrin. An isothermal titration calorimeter study
Eli, Wumanjiang,Chen, Wenhai,Xue, Qunji
, p. 1283 - 1296 (2007/10/03)
The association of a series of anionic surfactants (CnH2n+1SO4Na, n = 6, 8, 10, 12, 14) with β-cyclodextrin was studied by means of the isothermal titration calorimeter (i.t.c.) at T = 298.15 K. For these types of inclusion complexes, the results agreed well with a 1:1 association mode. Apparent values for the association constants, and changes in the standard molar Gibbs energies, enthalpies, and entropies were derived for the association process. The results indicated that the association of surfactants with β-cyclodextrin is characterized by both favourable enthalpy and favourable entropy changes. The results also demonstrated that the longer the alkyl chain of the anionic surfactant, the greater the association constant with β-cyclodextrin.
Influence of Chain Length on the Sphere-to-Rod Transition in Alkyl Sulfate Micelles
Missel, Paul J.,Mazer, Norman A.,Benedek, George B.,Carey, Martin C.
, p. 1264 - 1277 (2007/10/02)
Using Quasielastic light scattering spectroscopy (QLS) we have deduced the mean hydrodynamic radius (Rh) of alkyl sulfate micelles as functions of chain length (number of carbons nc = 8-16), temperature (0-85 deg C), detergent concentration (0.01-4g/dL), and NaCl concentration (0.1-2 M).In the region of low chain length (nc h values (extrapolated to the cmc) increase approximately linearly with the chain length.These results combained with Huisman's aggregation numbers (nw(cmc)) are consistent with a micellar shape that is close to spherical (axial ratio less than 2).Under conditions of high NaCl concentrations of high NaCl concentration the micelles exhibit a temperature-dependent growth from small spherical aggregates into long spherocylindrical micelles at concentrations above the cmc.With increasing chain length the temperature dependence of Rh becomes stronger and the NaCl and detergent concentrations needed for micellar growth become smaller.Light scattering intensity measurements confirm a rodlike growth for these micelles at all chain lengths.From these Rh measurements, values of the thermodynamic parameter K governing the sphere-to-rod transition are determined by using an extension of our previous thermodynamic model (Missel et al., J.Phys.Chem., 84, 1044 (1980)).A quantitative analysis of the dependence of K on chain length, temperature, and NaCl concentration provides new insights into energetic factors which govern the structure and growth of micelles.
