http://wwwcourses.sens.buffalo.edu/ce435/Pedersen97.pdf

Analysis of small-angle scattering data from colloids and polymer solutions: modeling and least-squares fitting

In certain surfactant solutions, such as aqueous cetyltrimethylammonium bromide (CTAB) in 0.1 M KBr, the amphiphiles are found to assemble reversibly into long, flexible worm-like micelles. Above a few per cent surfactant, these form an entangled viscoelastic fluid, reminiscent of a polymer solution. The authors review some recent experimental and theoretical progress concerning the equilibrium statistics and dynamics of these systems, which differ from normal polymer solutions in that the chains can break and reform reversibly.

http://iopscience.iop.org/article/10.1088/0953-8984/2/33/001/pdf

Statics and dynamics of worm-like surfactant micelles

Dimeric and oligomeric surfactants. Behavior at interfaces and in aqueous solution: a review.

Oil and water do not mix. The disaffinity of oil for water, with its unusual temperature dependence, is called the hydrophobic effect. It is important to understand the factors underlying the hydrophobic effect because they appear to play key roles in membrane and micelle formation, protein folding, ligand-protein and protein−protein binding, chromatographic retention, possibly nucleic acid interactions, and the partitioning of drugs, metabolites, and toxins throughout the environment and living systems. Here, we survey experimental and theoretical studies of nonpolar solute partitioning into water. We note that the hydrophobic effect is not just due to “water ordering” and not merely due to small size effects of water. The properties vary substantially with temperature and solute shape. Also, we discuss the limitations of using oil/water partitioning as the basis for some thermodynamic models in chemistry and biology.

https://pubs.acs.org/doi/pdf/10.1021/jp020104r

A View of the Hydrophobic Effect

The concept of molecular packing parameter is widely invoked in the literature to explain, rationalize and even predict molecular self-assembly in surfactant solutions. The molecular packing parameter is defined as vo/aelo, where vo is the surfactant tail volume, lo is the tail length, and ae is the equilibrium area per molecule at the aggregate surface. A particular value of the molecular packing parameter can be translated via simple geometrical relations into specific shape and size of the equilibrium aggregate. This is the predictive application of the concept of molecular packing parameter, as discussed in the literature. In calculating the packing parameter, the dominant notion in the literature is that the surfactant headgroup determines the surface area per molecule of equilibrium aggregates ae. It follows that, given a headgroup, the molecular packing parameter vo/aelo is fixed, because the volume-to-length ratio (vo/lo) of the tail is a constant independent of the tail length for common surfacta...

Molecular Packing Parameter and Surfactant Self-Assembly: The Neglected Role of the Surfactant Tail†

A strong increase has been measured in the size and polydispersity of sodium dodecyl sulfate (SDS) micelles on increasing the detergent concentration in solutions containing high salt (NaCl) concentration. The mean hydrodynamic radius and the polydispersity of the micelles were measured. A thermodynamic theory of micelle formation and growth is presented. This theory makes use of the experimentally established result that the micelles have the shape of prolate spherocylinders. The micellar size and polydispersity is determined at each temperature and salt concentration by 2 chemical potentials. These are the chemical potential changes associated with transferring a detergent monomer from the solvent to either the cylindrical or spherical region of the micelle. Using only these 2 chemical potentials as parameters, one can predict accurately the hydrodynamic radius, the polydispersity, and the scattered light intensity over the entire experimental range of detergent concentration, temperature, and salt concentration. 43 references.

Thermodynamic analysis of the growth of sodium dodecyl sulfate micelles

Deduction of micellar shape from angular dissymmetry measurements of light scattered from aqueous sodium dodecyl sulfate solutions at high sodium chloride concentrations

Influence of chain length on the sphere-to-rod transition in alkyl sulfate micelles

L'influence de la nature du contre ion des agents de surface anioniques (alkylsulfate) sur la taille et la forme des micelles est etudiee par diffusion quasi elastique de la lumiere

Influence of alkali-metal counterion identity on the sphere-to-rod transition in alkyl sulfate micelles

Above the CMC, alkyl sulfate micelles exhibit a sphere-to-rod transitition which is dependent on temperature, NaC1 concentration and detergent concentration. Using the techniques of quasielastic light scattering we have studied this transition as a function of these variables and have also investigated the effects of alkyl chain length, counter-ion size and urea concentration on micellar growth. These experimental data are interpreted using a quantitative model for the sphere-to-rod transition in which a thermodynamic parameter K, which measures the difference in chemical potential for a detergent molecule in the spherical or cylindrical micellar structure, is seen to play a fundamental role. The contributions of electrostatic and hydrophobic interactions to the value of K are discussed using a theoretical equation and are assessed quantitatively from the experimental deductions of K as a function of NaC1 concentration, temperature and the other variables.

Paul J. Missel

Papers

Thermodynamic analysis of the growth of sodium dodecyl sulfate micelles

Deduction of micellar shape from angular dissymmetry measurements of light scattered from aqueous sodium dodecyl sulfate solutions at high sodium chloride concentrations

Influence of chain length on the sphere-to-rod transition in alkyl sulfate micelles

Influence of alkali-metal counterion identity on the sphere-to-rod transition in alkyl sulfate micelles

Thermodynamics of the Sphere-to-Rod Transition in Alkyl Sulfate Micelles