Micelles quasi-elastic light scattering

Micellization of PS-PMA diblock and triblock copolymers in 80 20 dioxane water mixtures was investigated by Qin et al. (1994) using static and quasi-elastic light scattering, differential refractometry, viscomelry, sedimentation... 

Fig. 4.2. Mean radius of gyration plotted versus the mean hydrodynamic radius for different micelle shapes according to theoretical predictions (solid lines). Circles give experimental quasi-elastic light scattering results for SDS micelles at different temperatures in 0.6 M NaCl. (From Ref.34 )...

Effect of Radiation Dose on Micellar Properties. Figure 1 shows the concentration dependence of the micellar diffusion coefficient at 40° as determined by quasi-elastic light scattering (QELS) for solutions subjected to radiation doses of up to 4.56 Mrad. Limiting diffusion coefficients, D0>were obtained by extrapolation of data for dilute solutions (<0.05%) to zero concentration, the critical micelle concentration (CMC) being negligibly low for this poloxamer ( 1 ). 

Evcms DF, Yamouchi A, Wei GJ et al (1983) Micelle size in ethylammonium nitrate as determined by classical and quasi-elastic light scattering. J Phys Chem 87 3537-3541... 

Schematic models for the expanded structure of bile acid-phosphatidylcholine mixed micelles are shown in Fig. 2B. The original model was proposed by Small in 1967 (S36). In this model the mixed micelle consisted of a phospholipid bilayer disk surrounded on its perimeter by bile acid molecules, which were oriented with their hydrophilic surhices in contact with aqueous solvent and their hydrophobic sur ces interacting with the hydrocarbon chains of the phosphohpid molecules. This model has recently been revised, based on further studies of mixed micelles using quasi-elastic light scattering spectroscopy (M20). In a new model for the molecular structure of bile acid-phospholipid mixed micelles. Mazer et al. (M20) propose a mixed disk, in which bile acids are found not only on the perimeter of phospholipid bilayers, but also incorporated within their interior in high concentrations (Fig. 2B). The size of these mixed micelles was estimated to be as high as 200 to 400 A in radius in some solutions, and disk-shaped particles in this size range were observed by transmission electron microscopy (M20). Micellar aggregates similar in size and structure to those found in model bile solutions have been demonstrated in dog bile (M22).

The problem of particle nucleation was first addressed in the 1980s by Candau and coworkers [14,104] for the case of water-in-oil microemulsions. Their studies concerned the polymerization of acrylamide inside water-swollen micelles stabilized by AOT and dispersed in toluene. A thorough investigation of the structures prior to and after polymerization by elastic and quasi-elastic light scattering (QELS), viscomelry, and ultracentrifugation experiments yielded two key experimental results ... 

A major advantage of quasi-elastic light scattering is that analysis of the data allows one to calculate the radius of the micelles and to examine the nature of the electrostatic and van der Waals interactions between the micelles [46-48]. It is important to remember that intermicellar interactions must also be taken into account when methods such as classical Ught scattering or sedimentation are used for determination of micellar size [41]. 

Dubin PL, Davis DD (1984) Quasi elastic light scattering of polyelectrolyte micelle complexes. Macromoleculaes 17(6) 1294—1296... 

Kiserow D, Prochazka K, Ramireddy C, Tuzar Z, Mimk P, Webber SE (1992) Fluorometric and quasi-elastic light-scattering study of the solubilization of nonpolar low-molar mass compounds into water-soluble block-copolymer micelles. Mactomolecules 25(l) 461-469. doi 10.1021/ma00027a072... 

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