Micellar weight

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. 

This paper reports the systematic study of the apparent anhydrous micellar weights of the three principal bile salts found in man and their glycine and taurine conjugates in respect to bile salt concentration, counterion concentration, temperature, pH, and urea concentration. On the basis of these studies, model structures of bile salt micelles are proposed. Sodium dehydrocholate, a triketo bile salt, was also studied but was not found to form micelles. 

Table I records the conditions of the experiment (temperature, pH, and solvent) the experimental data used to calculate the apparent micellar weights by equilibrium ultracentrifugation [V, r, C0, (dc)/ (dr)r = r, or], and the results (apparent micellar weight, M, and apparent aggregation number, Ag ), for each bile salt studied. The results are illustrated in Figures 1 to 10.

Figure 1. Apparent micellar weight by equilibrium ultra-centrifugation vs. initial concentration difference...

Micellar weight extrapolated to zero initial concentration difference. 

K. Kuriyama, Temperature dependence of micellar weight of nonionic surfactant in the presence of various additives, Part 2, Addition of sodium chloride and calcium chloride, Kolloid Z.Z. Polym. 181 (1962) 144-149. 

Fig. 21. Micellar weight versus dielectric constant e for natural lecithin. Lightscattering in single (o), (x) in mixed solvents ( ) diffusion-viscosity measurements (mean values). [Kolloid Z. Polym. 195, w 27 (1964)1...

Figure 3. Effect of surfactant ration on micellar weight of mixed surfactant (SLS SC-840 system)...

Np (19). Since the micellar weight determinations in this series of experiments were limited to the range of r = 0.05 to r = 0.5, which was also the range of r-values within which the maximum p(n) happened, the selected three values of surfactant ratios for the confirmation tests were considered proper and sufficient. 

We hav shown that with the use of a mixed surfactant system in styrene emulsion polymerization, the composition of the mixed surfactant has an effect on the rate of polymerization, the number of particles formed and the particle size distribution. We have also shown that a change in the ratio, r of the two surfactants in the mixture results in a considerable change in the micellar weight of the resultant mixed micelles. We have thus proposed and proven that the efficiency of nucleation of particles (even when the same number of micelles is used in the experiment) is dependent on the size of the mixed micelle, and that there is an optimum size at which the polymerization rate is the fastest and the particle size distribution is the narrowest. 

Table 6.4 Values of cmc and micellar weights of hexadecyl polyoxyethyl( ene ethers CH3(CH3),j(CH2CH2) OH"...

Solvent Benzene," % Biphenyl," % Micellar Weight, gmol ... 

Determination of Micellar Weight Determination of micellar weights for DSS in anhydrous and hydrous hydrocarbon solutions has been made by means of light scattering (34). 

Tausk RJ, van Esch J, Karmiggelt J, Voordouw G, Overbeek JT (1974) Physical chemical studies of short-chain lecithin homologues. 11. Micellar weights of dUiexanoyl- and diheptanoyllecithin. Biophys Chem 1974 184-203... 

Relative Molar Mass of Micelles. The mass of 1 mole of micelles (actually it is the mass of 1 mole of micelles divided by the mass of mole of C). Synonyms include relative micellar mass and relative micellar weight. 

Method T, °C Counterion cone. (A/) and type pH Anhydrous micellar weight Aggrega- tion number Reference... 

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