Kinetics, worm micelles

Release kinetics of taxol from OCL worm micelles was studied by dialysis method under sink condition . Figure 7 shows the percentage of taxol released from OCLl and OCL3 worm micelles versus time at 37 C, under pH 5 Hepes and pH 7 PBS physiological buffers respectively. After an initial burst release, typical for polymeric micelle systems (7), a much slower and sustained release... 

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. 

Zhang and coworkers studied the differences between self-assembly of cyclic and linear nonionic amphiphilic copolypeptoids of Al-methyl- and A -decylglycine [117]. The differences were minor with respect to the final product but differed in the formation kinetics. Initially, spherical micelles formed in methanolic or aqueous solutions/suspensions. However, within a few days, both materials eventually formed cylindrical (worm-like) micelles. These micelles were only a few nanometers in diameter but several microns in length. 

The worm-to-sphere transition occurs with bulb formation at the end of the worm, consistent with release of spherical micelles from the end. Figure 5. (26) Conservation of mass allows one to show that the hydrolysis kinetics is the rate ... 

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