Sodium octadecyl sulfate

In the present study, the monolayer technique is used to investigate the surface properties of octadecyldimethylamine oxide and sodium octadecyl sulfate, as single component films and in combination. The interpretation of the results provides a direct understanding of the mechanism of interaction between these two surface active agents. 

Octadecyldimethylamine oxide (CieDAO) was a commercial sample from Onyx Chemical Company, Jersey City, N. J. (25% active). After evaporating the solvent in a rotary evaporator under reduced pressure, the crude product was recrystallised several times from ethyl acetate. The final product was dried and stored in vacuo over P2O5. Sodium octadecyl sulfate (SODS) was a sample prepared in this laboratory previously, and was recrystallised from ethanol before use. Sodium dodecyl sulfate (SDS) was obtained from Aldrich Chemical Company, and was of 98% purity. It was further purified by repeated crystallisation from ethanol followed by ether extraction. Benzene and methanol were gold-label reagent grade, purchased from Aldrich Chemical Company (Metuchen, N. J.). 

Figure 1. Surface pressure-area isotherms for sodium octadecyl sulfate at the air-0.01 M sodium chloride solution interface. 0 A 5°C, O 20°C.

Figure 7. Surface pressure-area isotherms for an equimolar mixture of sodium octadecyl sulfate and octadecyltrimethylammonium bromide at the n-heptane-O.OOlM sodium chloride interface. ...

Using surface pressure (u)-area (A) isotherms for sodium octadecyl sulfate (C18 sulfate) and octadecyl trimethylam-monium bromide (C18 TAB) monolayers spread at the air/water (A/W) and n-heptane/water (O/W) interfaces, we show that the Davies-Guastalla and Davies surface equations of state are not followed over a wide range of temperature and salt concentration. We attribute the discrepancies to Davies incorrect estimate of the chain-cohesion term at the A/W interface, the inadequacy of the electrical contribution to n at all but the highest A studied, and a possible chain-cohesion term at the O/W interface. 

We describe in a companion paper (33) the salient features of our procedures for measuring low surface pressures, and we provide n-A isotherms for octadecyl trimethylammonium bromide (Ci8 TAB) and sodium octadecyl sulfate (Ci8 sulfate) monolayers spread at A/W and O/W interfaces. Here we extend some of these data to higher A using, in some instances, some of our earlier reported measurements. We have also taken from literature the few reported isotherms for dilute charged monolayers and discuss them in the light of our results and the predictions of Equations 7 and 8. 

In the vibrating plate studies the liquid surface was formed in a waxed Langmuir-Adam trough in which the surface could be cleaned by waxed slides. Details of how cleanliness was controlled, how monolayers were spread, and how surface pressures were measured are described elsewhere (25). We studied numerous monolayers but only report sodium octadecyl sulfate and distearoyl lecithin monolayers. 

Sodium 2-[(octadecylamino) carbonyl] benzoate. See Sodium phthalate stearyl amide Sodium octadecyl sulfate. See Sodium stearyl sulfate... 

Anionic surfactant sodium hexa-decyl sulfate, sodium octadecyl sulfate... 

Sodium octadecyl sulfate. See Sodium stearyl sulfate Sodium octadecyl sulfosuccinamate. See Sodium stearyl sulfosuccinamate Sodium octane sulfonate. See Sodium caprylyl sulfonate Sodium octanoate Sodium n-octanoate. See Sodium caprylate Sodium octoxynol-2 ethane sulfonate CAS 2917-94-4 67923-87-9 EINECS/ELINCS 220-851-3 267-791-4 Synonyms Entsufon Entsufon sodium 2-[2-[2-Octylphenoxy) ethoxy] ethoxy] ethanesulfonic acid, sodium sail Sodium 2-[2-[2-[4-(1,1,3,3-tetramethyibutyi) phenoxy] ethoxy] ethoxy] ethanesuifonate Classification Organic compd. 

Weil et al. [58] studied the hydrolysis of sodium hexadecyl ether (1 PrO) and octadecyl ether (1 PrO) sulfates in comparison to sodium octadecyl ether (1 EO) sulfate and sodium hexadecyl sulfate, and determined the kinetic constant ( j) for the first-order equation ... 

The hydrolysis of 0.05 N surfactant solutions was carried out in 0.05 N HC1 solution at 80°C. These constants demonstrate that propoxylated sulfates are less stable than those ethoxylated and all them less stable than alcohol sulfates. The time for 50% hydrolysis was 92 min for sodium hexadecyl ether (1 PrO) sulfate, 98 min for sodium octadecyl ether (1 PrO) sulfate, 136 min for sodium octadecyl ether (1 EO) sulfate, and 187 min for sodium hexadecyl sulfate... 

Abbreviations. aT = a-tocopherol, AC = aminocoumarin, ANS = l-anilino-8-naphthalenesulfonic acid, CTAB = cetyltrimethylammonium bromide, DPPC = dipalmitoylphosphatidylcholine, DPPH — l,l-diphenyl-2-picrylhydrazyl, DSHA = Ai-dansylhexadecylamine, GMO = glycerol monooleate, HC = hydrocoumarin, N,N -DOC = JV,JV -di(octadecyl)oxacarbocyanine, PC = phosphatidylcholine, p-CUO = pyrene caroboxaldehyde, SDES — sodium decyl sulfate, SDS — sodium dodecyl sulfate, STS = sodium tetradecyl sulfate. 

Octadecyl sulfate sodium salt (Ci8H37-0-S03 Na+) was examined by laser desorption (LD) Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) in the negative mode resulting in [M - H] ions. Little fragmentation was observed under these conditions [28]. 

On the other hand, sodium decyl sulfate, sodium dodecyl sulfate, and a sodium hexadecyl-octadecyl sulfate mixture result in equal PLMA MW for equal surfactant concentrations. These anionic surfactant concentrations are at or above their CMCs. That there is little or no influence on the aggregation number of the mixed micelles as the anionic surfactant tail varies from decyl to octadecyl is an indication of the importance of steric and electrostatic effects in the head-group region in these mixed micelles, at least for the 60 40 nonionic-anionic composition investigated here (34, 35). 

Surfactant concentration (varied after polymerization) greatly affects the viscosity of associating polymer systems. Iliopoulos et al. studied the interactions between sodium dodecyl sulfate (SDS) and hydrophobically modified polyfsodium acrylate) with 1 or 3 mole percent of octadecyl side groups [85]. A viscosity maximum occurred at a surfactant concentration close to or lower than the critical micelle concentration (CMC). Viscosity increases of up to 5 orders of magnitude were observed. Glass et al. observed similar behavior with hydrophobically modified HEC polymers. [100] The low-shear viscosity of hydrophobically modified HEC showed a maximum at the CMC of sodium oleate. HEUR thickeners showed the same type of behavior with both anionic (SDS) and nonionic surfactants. At the critical micelle concentration, the micelles can effectively cross-link the associating polymer if more than one hydrophobe from different polymer chains is incorporated into a micelle. Above the CMC, the number of micelles per polymer-bound hydrophobe increases, and the micelles can no longer effectively cross-link the polymer. As a result, viscosity diminishes. 

Hazardous Ingredients Sodium dodecyl sulfate (1%), formaldehyde (0.1%), a-octadecyl-m-hydroxy polyglycol ether (1%), a-isotridecyl-m-hydroxypolyglyco-lether (< 5%)... 

Octadecyl sulfate, sodium salt. See Sodium stearyl sulfate N-Octadecyl-N-(sulfosuccinyl) aspartic acid, tetrasodium salt. SeeTetrasodium dicarboxyethyl stearyl sulfosuccinamate Octadecyl trimethyl ammonium bromide Octadecyltrimethylammonium bromide. See Steartrimonium bromide Octadecyl trimethyl ammonium chloride. See Steartrimonium chloride 2,2,3,3,5,5,6,6-Octafluoro-4-(trifluoromethyl)morpholine. See Perfluoro-N-meth-ylmorpholine... 

Ethoxylation of the base alcohol always improves the solubility of the sulfate. As an example, sodium hexadecyl ether (2 EO) sulfate gives a clear 10% solution in water at 40°C, which becomes a viscous gel at 30°C [59]. Alcohol ether sulfates are also more soluble in organic solvents than the corresponding alcohol sulfates. Sodium hexadecyl and octadecyl ether (2 EO) sulfates are soluble at 1% concentration in lubricating oil, at 2.5% in benzene and chloroform, and at 5% in tetrachloroethylene, whereas alcohol-ethoxylated sulfates with 10 mol of ethylene oxide are soluble at 5% in lubricating oil [59]. 

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