Water potassium laurate

Discussion. We can now propose a coarse description of the paraffinic medium in a lamellar lyotropic mesophase (potassium laurate-water). Fast translational diffusion, with D 10"6 at 90 °C, occurs while the chain conformation changes. The characteristic times of the chain deformations are distributed up to 3.10"6 sec at 90 °C. Presence of the soap-water interface and of neighboring molecules limits the number of conformations accessible to the chains. These findings confirm the concept of the paraffinic medium as an anisotropic liquid. One must also compare the frequencies of the slowest deformation mode (106 Hz) and of the local diffusive jump (109 Hz). When one molecule wants to slip by the side of another, the way has to be free. If the swinging motions of the molecules, or their slowest deformation modes, were uncorrelated, the molecules would have to wait about 10"6 sec between two diffusive jumps. The rapid diffusion could then be understood if the slow motions were collective motions in the lamellae. In this respect, the slow motions could depend on the macroscopic structure (lamellar or cylindrical, for example)... 

Figure 7. Positional dependence of the bond order parameter, Srj)> for potassium laurate-water (79 21 wt %) at 82°C. Data from Ref. 11. (with permission from North Holland Publ. Co.)...

Hayduk, W. and Laudie, H. "Vinyl chloride gas compressibility and solubility in water and aqueous potassium laurate solutions, J. Chem. Eng. Data, 19(3) 253-257, 1974a. 

Figure 1 shows the results obtained by Francois and Skoulios (27) on the conductivity of various liquid crystalline phases in the binary systems water-sodium lauryl sulfate and water-potassium laurate at 50 °C. As might be expected, the water-continuous normal hexagonal phase has the highest conductivity among the liquid crystals while the lamellar phase with its bimolecular leaflets of surfactant has the lowest conductivity. Francois (28) has presented data on the conductivity of the hexagonal phases of other soaps. She has also discussed the mechanism of ion transport in the hexagonal phase and its similarity to ion transport in aqueous solutions of rodlike polyelectrolytes. 

Figure 1. Electrical conductivity of liquid crystalline phases in water-sodium lauryl sulfate (Curve 1) and water-potassium laurate (Curve II) systems (27).

With spin echo NMR techniques, Charvolin and Rigny (40) found a diffusion coefficient of about 2 X 10"6 cm2/sec for potassium laurate in the cubic liquid crystalline phase it forms with water. 

A spectrum of perdeuterated potassium laurate in oriented soap-water multilayers (5) is presented in Figure 2. The measured quadrupolar coupling constants are much smaller than those of a static C-D bond, which are about 167 kHz (6) the residual quadrupolar splittings... 

The most effective additives for increasing the stability of the foam produced by surfactant solutions appear to be long-chain, often water-insoluble, polar compounds with straight-chain hydrocarbon groups of approximately the same length as the hydrophobic group of the surfactant. Examples are lauryl alcohol for use with sodium dodecyl sulfate, Af,/V-bis(hydroxyethyl) lauramide for use with dodecylbenzenesulfonate, lauric acid for use with potassium laurate, and N,N-dimethyldodecylamine oxide for use with dodecylbenzenesulfonate and other anionics. 

It may be mentioned that the stearate above i 5 normal is hardly a solution, 1 5N sodium stearate at 90° is a viscid gum On the other hand, 2 oN potassium laurate solution with a similarly shaped curve is a clear oily liquid The form of the curve is thus due to the constituents in the system and is not due to mechanical effects, eg gel formation, skins on the surface, or other changes of state The effect is also not due to hystensis, as is the case m the dehydration of certain gels, for it is independent of the age or method of preparation of the soap solution or whether water may have been previously added or taken away It will be pointed out later that the existence of the minimum m the boiling pomt nse is due to dehydration of the colloidal constituents, thereby releasing a quantity of solvent which effectively dilutes the solution and thus produces a diminished nse in the boiling point Were it not for this, the boiling point would nse steadily all the way with increase m concentration... 

In certain cases, nematic (orientational but not positional) order may be observed in phases of (relatively small) micellar rods (canonic) or disks (discotic) [177], which are associated with lower temperature hexagonal and lamellar phases, respectively [178]. (See Fig. 17.) The nematic isotropic phases were thought to be built up of discrete aggregates of different shapes, but the presence of continuous aggregates has also been recently suggested in this case [178]. Some systems (e.g., potassium laurate-decanol-water) form biaxial nematic phases. In this case, the micelles are believed to be neither rods nor disks but rather to... 

The use of soaps to solubilize phenols in water, for use as disinfectants, depends on the formation of mixed micelles of the soap and the phenol. It has been found that variation in the proportion of soap to phenol leads to several zones, as shown in Fig. 14.2 (Berry, Cook and Wills, 1956). The first of these exists below 0.03 M potassium laurate and is poorly bactericidal the maximal bactericidal effect is obtained when the soap reaches 0.03 M, a figure which is identical with the critical micelle concentration for this soap. It was concluded that this bactericidal action is a combined attack of the phenol (mainly) and the soap on the protoplasmic membrane (see Section 14.3 for membrane damage). The next zone, up to 0.045 M soap, is one of greatly diminished bactericidal effect. The interpretation is that the phenol has entered the micelles, many more of which must have formed, and hence little of it is available for disinfection. When still more soap is introduced, a final zone (vigorous disinfection) appears, due to the toxicity of the soap itself All the phenols commonly used as disinfectants, including j -chloro-m-xylenol, form zones like these. 

When molecules are not so simple as rigid rods or discs, one may introduce apparent partial order parameters different for different molecular moieties. This is especially evident for lyotropic liquid crystals [21], such as, for instance, the lamellar phase formed by surfactants in water, see Fig. 3.22b. A good example is a water solution of potassium laurate. A flexible hydrocarbon chain K-CH2-CH2-CD2-CH2-. can be deuterated with a position of deuterium label varied along the chain, as shown by in Fig. 3.22a. Then, by the NMR technique sensitive only to deuterium nuclei, the apparent order parameter of the corresponding chain link can be determined. As shown in Fig. 3.23, it decreases with increasing the distance from the potassium atom due to flexibility of the hydrocarbon chain. Thus, we can say that the hydrocarbon tail is solid at the left end and liquid at the right one [22]. 

Yu, L.J., Saupe, A. Observation of a biaxial nematic phase in potassium-laurate -1-decanol-water mixtures. Phys. Rev. Lett. 45, 1(X)0 (1980)... 

Riegelmann et al. [93] studied various aromatic compounds solubilized in aqueous solutions of potassium laurate, dodecylamine hydrochloride, and a polyoxyethylene ether of dodecanol (Brij 35). The ultraviolet spectra of ethylbenzene in these micellar solutions were very similar to those in non-polar solvents (see Fig. 5.10) and it was concluded that this solubilizate resided completely in the micellar core. Some regions of the spectra of solubilized naphthalene, anthracene and azobenzene, on the other hand, showed similarities with the spectra of these compounds in water, whilst other regions resembled the spectra in non-polar solvents. The suggestion was made that these compounds were solubilized in such a way as to be in partial contact with both the polar micellar surface and the non-polar micellar core, i.e. a position of deep penetration. By similar reasoning it was concluded that o-nitroaniline was located at a position of short penetration whereas dimethylphthalate, whose spectrum closely resembled the spectrum in water, was thought to be adsorbed on the micellar surface. 

Solutions of phenols in ionic systems exhibit similar behaviour. An initial fall in the solubility of 2-hydroxyphenol and 4-benzylphenol in potassium laurate solutions was noted below the CMC of the soap [17]. Few workers have commented on this insolubilization compounds with very low water solubility possibly do not show this property. That it is not restricted to phenols is shown by the results of Heller and Klevens [18] for ethyl benzene in potassium laurate. Ethyl benzene has a solubility in water similar to that of 4-benzylphenol. 

In lyotropic liquid crystals, uniaxial negative nematics (Nl, i.e. disk-like phase) were found in aqueous solutions of potassium laurate (KL), 1-decanol, and potassium chloride [43]. Within a very narrow temperature and concentration range of a heavy water solution of this ternary mixture, Yu and Saupe [8] found a novel phase diagram (see Fig. 3). In this phase diagram, Nc is uniaxial positive (rod-like). Between the... 

Diffusivities of binary, ternary and multi-component liquid crystalline mixtures, e.g. of soap (potassium laurate (PL), water [25, 58], and lipid (dipalmitoylphosphatidylcho-line (DPPC) [25, 59] systems in lamellar, hexagonal, cubic, nematic and micellar mesophases [25,60,61] have been studied extensively by pulsed-field-gradient NMR [25] and optical techniques [62], partly because of their intimate relation to the structure and dynamical performance of biological membranes [18]. The main distinction from thermotropic phases is that for layered structures a noticeable diffusion occurs only within the layers (i.e. lateral, frequently written as Dl, but in our notation DjJ, whereas it is negligibly small and difficult to detect across the layers [60-62] (transverse migration, for bilayers denoted by flip-flop ) so the mobility is essentially two dimensional, and the anisotropy ratio is so great that it is seldom specified explicit-... 

Figure 4 Schematic view of the cylindrical (A), ribbon (B) and lamellar (C) lyotropic aggregates along with their corresponding 2 H NMR spectral patterns recorded for a potassium palmitate-ds in a mixture with 7 wt% potassium laurate and 30 wt% water. Reproduced with kind permission from Kluwer Academic Publishers from Doane JW (1985) In Emsiey JW (ed) NMR of Liquid Crystals, p414. Dordrecht Reidel.

If a phase is of a sufficiently low symmetry, then the corresponding indicatrix will be a general ellipsoid, the three semi-major axes of which will be three principal refractive indices. For such an ellipsoid there are two directions for which the normal section is circular, so such phases have two optic axes and are known as biaxial. The radius of the circular section corresponds to the intermediate principal refractive index. In 1980 [S] a biaxial phase was reported and characterised in a lyotropic nematic consisting of potassium laurate, 1-decanol and deuterated water. The biaxiality derives from asymmetric micelles, which are thought to be ellipsoidal in shape, having different dimensions in three... 

Cocoyl hydroxyethyl imidazoline Myristamine Oleyl hydroxyethyl imidazoline Soyamine softener, baby care Polyquatemium-22 softener, bath care Cetyl Cl 2-15 pareth-9-carboxylate Cocamidopropylamine oxide Isopropyl C12-15-pareth-9-carboxylate Polyglyceryl-3 laurate Potassium cocoyl hydrolyzed keratin softener, bitumen Coumarone/indene resin softener, boiier water treatment Sodium phosphate softener, boiler waters Sodium phosphate dibasic anhydrous softener, bubble baths Potassium cocoyl hydrolyzed collagen softener, building materials Isostearyl hydroxyethyl imidazoline softener, cellophane Ethylene glycol softener, cellulose paper Urea... 

The initiators can be water-soluble molecules (potassium or ammonium persulfate, hydrograi peroxide, and 2,2 -azobis(2-midinopropane) dihydrochloride), partially water-soluble peroxides (i.e. succinic acid peroxide and t-butyl hydroperoxide) or azo compounds, such as 4,4 -azobis(4-cyanopentanoic add). As regards the surfactants, anionic spedes, such as sodium or potassium stearate, laurate, palmitate, or sulfate and sulfonates (sodium lauryl sulfate and sodium dodecylbenzene sulfonate) are the most commonly used in ranulsion polymerization [16, 17]. By enhancing the surfactants concentration, the particle size decreases, while the particle number increases. 

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