Stiff surfactant systems

Stiff surfactant system, with rigid interface... 

Another force [57, 58] occurs in a multilayered system, like a swollen lamellar phase of surfactant bilayers or phospholipid vesicles. Shape fluctuations in the bilayers can give rise to steric effects that are supposed to stabilise such systems where the van der Waals and double-layer forces are very weak, as they often are. The magnitude of such fluctuations depends on the "stiffness" of die bilayer. The status of these forces is the subject of an active debate and imclear. 

Lastly, we have determined that in addition to polymer structure, the addition order of materials, such as polymer, surfactant and salt, to a formulation affects the compositional range of coacervate formation and the coacervation mechanism. Depending on the flexibility of the polymer structure, the mechanisms of coacervation in the presence of added electrolyte can vary. Poly (4-vinyl pyridine)-LAS-NaCl systems show a polymer collapse mechanism with the formation of a super-salt when salt and polymer are pre-mbced. However, for the stiff cellulosic polymers, the pre-mixing of salt and polymer before surfactant addition enhances micelle-bridging without complete polymer collapse. Also, the addition... 

The results obtained establish that the entropy of chain packing plays a central role in the formation of micelles in the class of models used in this work. It seems possible that similar arguments should apply to micellization in nonionic surfactants although electrostatic effects are likely to be important in ionic systems. Work is now being undertaken to study the relative importance of chain length and chain stiffness on the entropy per monomer. 

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