Sodium dodecyl sulfate aggregation

The logarithm of the micellar molecular weight (M) and consequently the aggregation number of sodium dodecyl sulfate at 25°C in aqueous sodium chloride solutions is linearly related to the logarithm of the CMC plus the concentration of salt (Cs), both expressed in molar units, through two equations [116]. Below 0.45 M NaCl micelles are spherical or globular, and Eq. (18) applies ... 

Molecular micellar weights can be calculated from the aggregation number. In the case of sodium dodecyl sulfate it is around 15,000 (aggregation number = 52) and it increases to 30,000 (aggregation number = 104) in diluted NaCl solutions. 

The Diels-Alder reaction of methyl methacrylate with cyclopentadiene was studied [72] with solutions from three different regions of the pseudophase diagram for toluene, water and 2-propanol, in the absence and in the presence of surfactant [sodium dodecyl sulfate (SDS) and hexadecyltrimethylammonium bromide (HTAB)]. The composition of the three solutions (Table 6.11) corresponds to a W/O-fiE (A), a solution of small aggregates (B) and a normal ternary solution (C). The diastereoselectivity was practically constant in the absence and in the presence of surfactant a slight increase of endo adduct was observed in the C medium in the presence of surfactant. This suggests that the reaction probably occurs in the interphase and that the transition state has a similar environment in all three media. 

Much biochemical evidence shows that many if not all 7TM receptors have a strong tendency to aggregate both with themselves and with other 7TM receptors, as most clearly seen in multiple high-molecular-weight bands on sodium dodecyl sulfate (SDS) gels. These bands are by no means restricted to dimers as, in most cases, several higher order oligomeric structures are observed. This is an important point to consider when the functional correlation of dimer formation is addressed in non-family C receptors. 

Takagi, S., Takeda, K., and Shhoishi, M. 1982. Aggregation, configuration and particle size of lutein dispersed by sodium dodecyl sulfate in various salt concentrations. Agric. Biol. Chem.Tokyo 46 2217-2222. 

Much remains to be learned, however, regarding the limits of applicability of the fluorescence probe technique to aggregates in non-polar media. A number of obvious experiments are conspicuous by their absence from the published literature. For example, 1-pyrene carboxaldehyde is a well known probe which has been used to measure the microscopic polarity of sodium dodecyl sulfate micelles in aqueous medium (5) there is, however, no account of its use in non-polar media. 

Surfactants having a positive curvature, above a given concentration usually called the critical micellar concentration, cmc, self-assemble to form oil-in-water aggregates called normal micelles. The surfactant most often used is sodium dodecyl sulfate, Na(DS) or SDS. To make particles, the counterion of the surfactant is replaced by ions which participate in the chemical reaction. These are called functionalized surfactants. 

Addition of micelle-forming surfactants and sodium dodecyl sulfate (SDS), in particular, dramatically increased the stabilities of N-alkalygluconamide aggregates (Fig. 55) [377]. It was considered that the rate of dissolution of the incipient head-to-tail sheets of crystallization nuclei by the micellar aggregates exceeded the growth rate of the crystals. This rationalization is supported by the... 

Assuming the scattering centers are aggregates of sodium dodecyl sulfate molecules, estimate the number of these units in the aggregate. 

The aggregation number for sodium dodecyl sulfate increases with increasing amounts of the indifferent electrolyte NaCl. 

The aggregation number rt and radius of sodium dodecyl sulfate micelles (by light scattering) and the zeta potential (from electrophoresis, by an accurate formula) were determined in the presence of various concentrations of NaCl. ... 

A detailed study of the structure of the aggregates of the ionic surfactants in polyelectrolyte networks was presented in Refs. [66,68]. The dynamics of the changes in the microenvironment of the fluorescent probe, pyrene, in slightly crosslinked networks of poly(diallyldimethylammonium bromide) (PDADMAB) during diffusion of sodium dodecyl sulfate (SDS) in the gel phase has been investigated by means of fluorescence spectroscopy. In Ref. [66], an analogous investigation was reported for complexes formal by the sodium salt of PMAA with cetyltrimethylammonium bromide (CTAB). 

Ross, B. P., A. C. Braddy, R. P. McGeary, J. T. Blanch eld, L. Prokai, and I. Toth. 2004. Micellar aggregation and membrane partitioning of bile salts, fatty acids, sodium dodecyl sulfate, and sugar-conjugated fatty acids Correlation with hemolytic potency and implications for drug delivbtpl. Pharm. 1 233-245. 

Almgren. M., J. Van Stam, C. Lindblad, P. Stilbs, and P. Bahadur. 1991. Aggregation of polyethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymers in the presence of sodium dodecyl sulfate in aqueous solutiod.. Phys. Chem. 95 5677-5684. 

The phase separation behavior of a sample of poly(N-vinyl-2.pyrrolidone) (PVP) in aqueous Na2S04 (0.55 M) containing a surfactant, sodium dodecyl sulfate (SDS), was reported [83], This phenomenon was studied in function of temperature and surfactant concentration as independent variables. Without surfactant, the polymer exhibits a lower solution temperature (LCST) of 28°C, above which it precipitates. At SDS concentrations of only 300 mg L-1, aggregation was prevented and the behavior of isolated polymer molecules could be studied. 

Soft-core reverse micelles are spherical or ellipsoidal aggregates consisting of a water core separated from a continuous apolar phase by a surfactant shell. It is well known that in the absence of water, some surfactants such as sodium bis(2-ethylhexyl) sulfosuccinate (AOT) can form dry aggregates, while others such as sodium dodecyl sulfate (SDS) or hexadecyl-trimethylamonium bromide (CTAB) need a cosurfactant, e.g., a short chain alcohol, to form micelles. 

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