Micelle living polymer

The appearance of the local minimum in the concentration dependency of the relaxation time of the slow process for concentrated solutions can be connected also with formation of non-spherical micelles [140]. Actually, it is well-known that micelles change their shape with increasing concentration. The increase of the concentration of some counterions can lead to the formation of giant wormlike micelles (living polymers) [141]. In this case the equilibrium size distribution of micelles changes entirely and is described by an exponential law [141]... 

Computer Simulations of Living Polymers and Giant Micelles... 

Living polymers and wormlike micelles suggest an interesting field for basic research in which the constant process of scission and recombination of the... 

In contrast to statics, the relaxational kinetics of living polymers and of giant wormlike micelles is unique (and different in both cases). It is entirely determined by the processes of scission/recombination and results in a nonlinear approach to equilibrium. A comparison of simulational results and laboratory observations in this respect is still missing and would be highly desirable. 

To use templates or envelopes as a controlled reaction space was developed in the early 1980s, such as the use of inverse micelle technique (4). Another fundamental idea is to use the atomic periodicity of surfactant molecules by using them as surface ligands for sequential addition of anions and cations under the concept of semiconductive compounds like CdSe as a living polymer (3). 

The flow properties of disordered micellar phases are now reasonably well understood. For spherical micelles the viscosity can be estimated from modified hard-sphere-suspension theories, while for disordered semidilute cylindrical micelles the Cates theory of entangled living polymers provides at least a good starting point, and in some cases nearly quantitative prediction of rheological properties. 

Living polymers, exemplified by surfactant wormlike micelles, continue to prove fruitful for experimental rheology of transitions between different... 

Because of the interaction of the two complicated and not well-understood fields, turbulent flow and non-Newtonian fluids, understanding of DR mechanism(s) is still quite limited. Cates and coworkers (for example, Refs. " ) and a number of other investigators have done theoretical studies of the dynamics of self-assemblies of worm-like micelles. Because these so-called living polymers are subject to reversible scission and recombination, their relaxation behavior differs from reptating polymer chains. An additional form of stress relaxation is provided by continuous breaking and repair of the micellar chains. Thus, stress relaxation in micellar networks occurs through a combination of reptation and breaking. For rapid scission kinetics, linear viscoelastic (Maxwell) behavior is predicted and is observed for some surfactant systems at low frequencies. In many cationic surfactant systems, however, the observed behavior in Cole-Cole plots does not fit the Maxwell model. 

It is obvious that the kinetic theory of micellisation outlined above, cannot be applied to living polymers. For wormlike micelles one has to distinguish between several processes leading to disintegration and formation of micelles and to determine the corresponding characteristic times [141 - 145] ... 

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