The Dynamics of Micelle Formation

Abstract

The article presents kinetic data on micellar systems that were obtained with relaxation techniques. Problems that are relevant to the following topics are discussed in detail:1. Differences in the dynamic behaviour of micellar systems consisting of single-and double chain detergents. 2. The dynamics of micellar systems consisting of ionic detergents with hydrophobic counterions. 3. The dynamic behavior of micellar systems of perfluorated ionic detergents.For most of the systems two relaxation times could be observed which very often showed characteristic differences in their temperature and concentration dependence. The two relaxation processes were associated according to the theory of micelle formation by G. Aniansson and S. Wall to the shift of the micellar distribution curve and the change of the micelle concentration. The following parameters were evaluated from the data: The residence times of the detergent molecules inside the micelles, the mean aggregation number of the micelles, the width of the micellar distribution curves and the concentrations of the micellar nuclei and their aggregation numbers. Ber. Bunsenges. Phys. Chem. 82,988-1001 (1978) -0 Verlag Chemie, D-6940 Weinheim, 1978. 1. Die Unterschiede im dynamischen Verhalten von Mizellgleichgewichten bei ein-und zweikettigen Tensiden. 2. Das dynamische Verhalten von Mizellen aus ionogenen Tensiden mit hydrophoben Gegenionen. 3. Das dynamische Verhalten von Mizellen aus perfluorierten Tensiden. Bei den meisten Systemen konnten zwei Relaxationszeiten beobachtet werden, die fur die verschiedenen Systeme oft charakteristische Unterschiede in der Temperatur-und Konzentrationsabhangigkeit aufweisen. Die beiden Relaxationsprozesse wurden nach der Theorie der Mizellbildung von G. Aniansson und S. Wall der Verschiebung der Mizellverteilungskurve bei konstanter Mizellkonzentration und der Anderung der Mizellkonzentration zugeordnet. Aus den Relaxationszeiten wurden die Verweiizeiten der Tensidmolekiile in der Mizelle, die mittleren Aggregationszahlen der Mizellen, die Breite der Verteilungskurven und die Konzentration der Mizellkeime sowie deren Aggregationszahlen ermittelt. 9 -8t -6 'In Y ; $ 5m D -4 - -

CHLOROPHYLL PHOTOSENSITIZED ELECTRON TRANSFER IN PHOSPHOLIPID BILAYER VESICLE SYSTEMS: SECONDARY OXIDATION OF REDUCED VIOLOGEN ACCEPTORS BY Ru(NH3)63+

“…By fitting our data to this model, the values of kOff, k,,, and Kcq = k,,/kOff were determined. On theoretical grounds as well as experimental results obtained with viologens and other kinds of molecules (Anaisson et al, 1976;Hoffmann, 1978;Almgren et al, 1979;Tanford, 1980;Bolt and Turro, 1981;Tabushi and Kugimiya, 1984), the values of k,ff are expected to decrease exponentially with increasing length of the alkyl substituents on the viologen radicals, while Keq is expected to increase exponentially. The values of k,, should be nearly diffusion-controlled and thus be relatively insensitive to changes in the alkyl substituents.…”

Chlorophyll Photosensitized Electron Transfer in Phospholipid Bilayer Vesicle Systems: Correlations Between Kinetic Parameters and Solubilities of Viologen Acceptors *

“…2. The analysis will focus on the homogeneous viologen series C,V2+, because changes in the alkyl chain length ( n ) of surfactants such as the viologens systematically change the way that they distribute between the membrane and water phases (Aniansson et al, 1976;Hoffmann, 1978;Tanford, 1980;Tabushi and Kugimiya, 1984).…”

“…Since Ymin = kJ(k2 + k3) = 0.1, it follows that k3 > lo4 s-l and C2 = 20 x k3 > lo5 s-'. This lower limit on C2 (the rate constant for n = 0) is a reasonable value since, for example, the rate constant for the dissociation of naphthalene from detergent micelles is about lo5 s-l (Almgren et al, 1979;Thomas, 1984), and the corresponding values for ionic detergent monomers range from lo5 to lo9 s-l (Aniansson et al, 1976;Hoffmann, 1978).…”

“…The rate constants for such reactions have been measured for many kinds of molecules in micelles (Thomas et al, 1978;Almgren et al, 1979;Bolt and Turro, 1981; Thomas, 1984) and vesicles (Almgren, 1980). For homologous series of n-alkyl substituted molecules, the rate constants generally decrease exponentially as the number of methylene groups increase (Anians- son et al, 1976;Hoffmann, 1978;Bolt and Turro, 1981). Therefore, we assume thtt k4 depends exponentially on n in the series C,V* according to Eq.…”

Substrate‐Induced Self‐Assembly of Cooperative Catalysts

“…Indeed, it had been previously reported that an analogous surfactant with a shorter chain showed very low catalytic activity for the same reaction, which was attributed to the highly dynamic nature of the assemblies . To investigate this aspect in more detail, we decided to prepare and study a series of surfactant molecules with hydrophobic chains of varying lengths, from ethyl ( C 2 TACN ) through to stearyl ( C 18 TACN ) as the kinetic stability of surfactant‐based assemblies is known to increase with the lengthening of the alkyl chain . Figure a shows the transphosphorylation activity at different concentrations of surfactants and equimolar Zn 2+ in a buffered solution containing excess HPNPP (500 μ m ).…”