Surfactant sodium dodecyl sulphate

Homogeneous LaMn03 nanopowder with the size of 19-55 nm and with the specific surface area of 17-22 m2/g has been synthesized using a surfactant, sodium dodecyl sulphate (SDS) to prevent agglomeration [47], The sonochemically prepared LaMn03 showed a lower phase transformation temperature of 700°C, as compared to the LaMn03 prepared by other conventional methods which has been attributed to the homogenization caused by sonication. Also, a sintered density of 97% of the powders was achieved for the sonochemically prepared powders at low temperature than that of conventionally prepared powders. 

Surfactant (sodium dodecyl sulphate) Distilled water... 

I if>urc 3. Adsorption isotherms of model surfactants (sodium dodecyl sulphate (SDS), egg albumin. iml lecithin) and their mixtures (SI >S and leicthin, concentration ratio 1 5, and albumin and lecithin, (iiux-ntration ratio I I) in seawater. Dashed lines correspond to calculated isotherms. (Cosovic et al.,... 

The adsorption of the anionic surfactant sodium dodecyl sulphate (SDS), probably the most frequently studied surfactant and often used as model substance at the air/water and at the decane /interface is given in Fig. 1.5. The surface and interfacial tension have been plotted as a function of SDS concentration in the aqueous phase. From the slope of the tangents to the curves in Fig. 1.5 the interfacial excess concentration (adsorption density) F at different interfacial tensions can be calculated directly using Gibbs fundamental adsorption isotherm (see section 2.4.1),... 

Sperry et al. found that the addition of either the anionic surfactant sodium dodecyl sulphate or the nonionic surfactant Triton X-405 completely desorbed any hydroxyethyl cellulose from the surface of the latex particles. This meant that, even in the presence of free hydroxyethyl cellulose in the continuous phase, none of the flocculating polymer was attached to the surface. The latex particles in the presence of the sodium dodecyl sulphate (0-5%) were thus electrostatically stabilized whereas the nonionic Triton surfactant conferred steric stabilization. 

The migration of the surfactant sodium dodecyl sulphate to the film-air(F-A) and film-substrate(F-S) interfaces during coalescence of a methyl methacrylate-ethyl acrylate latex functionalised with methacrylic acid was monitored by IR and ATR-FTIR spectroscopic techniques. Both F-A and F-S interfaces showed surfactant enrichment, revealing a nearly parabolic distribution of surfactant throughout the film. 11 refs. 

Note, the course of y(t) is very typical for commercial surfactants which are usually mixtures of homologues or even various different compounds. A very famous example is the most frequently studied surfactant sodium dodecyl sulphate SDS, which is supplied as chemical by the homologous alcohol dodecanol (Vollhardt and Emrich 2000). 

The rheological properties of hydrophobe-modified alkali-swellable emulsion (HASE) thickener solution are studied, with emphasis on surfactant and electrolyte (NaCl) effect. Similar studies in model HASE thickeners have been reported. Two commercial HASE thickeners (HASE-615 and HASE-935) are examined for comparison. In the absence of SDS, the NaCl addition changes solution viscosity depending on the relative concentration of the NaCl and thickener. The viscosities of HASE type thickeners are enhanced by an anionic surfactant, sodium dodecyl sulphate (SDS) and viscosity maxima are observed due to mixed micelle formation among thickener hydrophobes and surfactants. The addition of NaCl suppresses the viscosity of HASE-615/ SDS solutions, with HASE-935 at higher concentrations actually increasing in viscosity with NaCl addition. 2 refs. USA... 

The anionic surfactant sodium dodecyl sulphate was used to form the aqueous micellar system. In order to ensure that no protonated or de-protonated species were participating in the reaction the pH behaviour of the system was studied spectro-photometrically in both water and micellar solutions. The approximate derived pK values in both bulk water and micellar SDS are shown below. 

In this work a 3ys pulse from a Rhodamine 6-G dye-laser was used to photochemically dissociate metal ion complexes, kinetic results being obtained from the subsequent recombination reactions. The ligand used to test the applicability of the approach was pyridine-2-azo-p-dimethylaniline (PADA) since the kinetics of its complexation have been studied in aqueous solution with Ni (aq) (4). The influence of micelles formed by the anionic surfactant sodium dodecyl sulphate (SDS) on this reaction was also investigated. The arrangement of the apparatus used is shown in figure (1),... 

Figure 4.28 Phase diagram of the anionic surfactant sodium dodecyl sulphate in water. [Redrawn from R Kekicheff and B. Cabane, Acta Cryst. B, 44,395, Copyright (1988), with permission from lUCr. http //journals.iucr.org]...

Fig. 3.9 shows the variation of the CMC with temperature for an ionized surfactant (sodium dodecyl sulphate) and a non-ionic surfactant (CjoEs)- The minimum in the curve for ionic surfactants occurs typically between 20 and 30° C. Isolated examples exist of minima in CMC-temperature curves for non-ionic surfactants, e.g. minima were noted at approximately 50° C in a series of octylphenoxyethoxyethanols with oxyethylene chain lengths of between 6 and 10 [141]. The general failure to detect minima in curves for non-ionics could conceivably be a consequence of a lack of data at sufficiently high temperatures. In many cases such measurements would not be feasible due to phase separation at elevated temperatures. The decrease in the CMC of ionic surfactants with temperature increase at lower temperatures is possibly due to dehydration of the monomers, whilst further temperature increase causes disruption of the structured water around the hydrophobic groups which opposes micellization. 

---