On the Interaction of Insoluble Alkyl Alcohol Monolayers with Aqueous Solutions of Ionic Surfactants

1980 ◽  
Vol 35 (12) ◽  
pp. 1395-1401
Author(s):  
H.-F. Eicke ◽  
M. K. Sharma
Keyword(s):  
Aqueous Solutions ◽  
Surfactant Concentration ◽  
Critical Concentration ◽  
Sodium Dodecyl ◽  
Ionic Surfactants ◽  
Conductivity Measurements ◽  
Surfactant Aggregates ◽  
Film Balance ◽  
Intermediate Surface ◽  
Alcohol Monolayers

Abstract The interaction between so-called alkyl alcohol (C5-C8) monolayers and aqueous solutions of ionic surfactants with different hydrophilic properties, i.e. calcium di-2-ethylhexyl sulfosuccinate and sodium dodecyl sulfate, has been studied with the help of a Langmuir-Adam film balance. A decrease or increase in surface pressure of the alkyl alcohol monolayers with the addition of surfactants is observed. The shift of the critical concentration (cmc) to increasing surfactant concentration occurs at intermediate surface pressures. This is interpreted as due to the formation of mixed alcohol-surfactant aggregates. The maximum of the cmc as a function of the pressure can be explained by a thermodynamic treatment assuming competition between a pressure dependent solubility of alcohol molecules and the formation of mixed alcohol surfactant complexes. The amount of alkyl alcohol required to react with the surfactant has been evaluated at different surface pressures, which shows values similar to those known from cosurfactant studies in the bulk phase. Critical micelle concentrations of the surfactants were verified by conductivity measurements.

scholarly journals Dispersions of Metal Oxides in the Presence of Anionic Surfactants

2018 ◽  
Vol 3 (1) ◽  
pp. 3 ◽  
Author(s):  
Leszek Ruchomski ◽  
Edward Mączka ◽  
Marek Kosmulski
Keyword(s):  
Metal Oxides ◽  
Surfactant Concentration ◽  
Critical Concentration ◽  
Supporting Electrolyte ◽  
Sodium Dodecyl ◽  
Sodium Dodecylsulfate ◽  
Solubility Limit ◽  
Ionic Surfactants ◽  
Liquid Ratio ◽  
High Concentration

We studied the behavior of dilute dispersions of nanoparticles of hematite, alumina, and titania in the presence of various concentrations of very pure sodium dodecyl-, tetradecyl-, and hexadecylsulfate. The concentrations studied were up to critical micelle concentration (CMC) for sodium dodecylsulfate, and up to the solubility limit in case of sodium tetradecyl- and hexadecylsulfate. The dispersions were adjusted to different pH (3–11), and 10−3 M NaCl was used as the supporting electrolyte. The solid-to-liquid ratio was strictly controlled in all dispersions, and the behavior of fresh dispersions was compared with dispersions aged for up to eight days. The presence of very low concentrations of ionic surfactants had rather insignificant effects on the ζ potentials of the particles. At sufficient concentrations of ionic surfactants the isoelectric point (IEP) of metal oxides shifted to low pH, and the long-chain surfactants were more efficient in shifting the IEP than their shorter-chain analogues. Once the surfactant concentration reached a critical value, the ζ potentials of the particles reached a pH-independent negative value, which did not change on further increase in the surfactant concentration and/or aging of the dispersion. This critical concentration increases with the solid-to-liquid ratio, and it is rather consistent (for certain oxides and certain surfactants) when it is expressed as the amount of surfactant per unit of surface area. Surprisingly, the surfactant-stabilized dispersions always showed a substantial degree of aggregation; that is, the particle size observed in dispersions by dynamic light scattering was higher than the size of particles observed in dry powders by electron microscopy. Apparently, in spite of relatively high ζ potentials (about 60 mV in absolute value), the surfactant-stabilized dispersions consist of aggregates rather than of primary particles, and in certain dispersions the high concentration of surfactant seems to induce aggregation rather than prevent it.

scholarly journals Association between Nonionic Amphiphilic Polymer and Ionic Surfactant in Aqueous Solutions: Effect of Polymer Hydrophobicity and Micellization

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1831 ◽  
Author(s):  
Samhitha Kancharla ◽  
Nathan A. Zoyhofski ◽  
Lucas Bufalini ◽  
Boris F. Chatelais ◽  
Paschalis Alexandridis
Keyword(s):  
Ethylene Oxide ◽  
Aqueous Solutions ◽  
Surfactant Concentration ◽  
Sodium Dodecyl ◽  
Amphiphilic Polymers ◽  
Pluronic F127 ◽  
Ionic Surfactant ◽  
Pluronic P123 ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

The interaction in aqueous solutions of surfactants with amphiphilic polymers can be more complex than the surfactant interactions with homopolymers. Interactions between the common ionic surfactant sodium dodecyl sulfate (SDS) and nonionic amphiphilic polymers of the poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) (PEO-PPO-PEO) type have been probed utilizing a variety of experimental techniques. The polymer amphiphiles studied here are Pluronic F127 (EO100PO65EO100) and Pluronic P123 (EO19PO69EO19), having the same length PPO block but different length PEO blocks and, accordingly, very different critical micellization concentrations (CMC). With increasing surfactant concentration in aqueous solutions of fixed polymer content, SDS interacts with unassociated PEO-PPO-PEO molecules to first form SDS-rich SDS/Pluronic assemblies and then free SDS micelles. SDS interacts with micellized PEO-PPO-PEO to form Pluronic-rich SDS/Pluronic assemblies, which upon further increase in surfactant concentration, break down and transition into SDS-rich SDS/Pluronic assemblies, followed by free SDS micelle formation. The SDS-rich SDS/Pluronic assemblies exhibit polyelectrolyte characteristics. The interactions and mode of association between nonionic macromolecular amphiphiles and short-chain ionic amphiphiles are affected by the polymer hydrophobicity and its concentration in the aqueous solution. For example, SDS binds to Pluronic F127 micelles at much lower concentrations (~0.01 mM) when compared to Pluronic P123 micelles (~1 mM). The critical association concentration (CAC) values of SDS in aqueous PEO-PPO-PEO solutions are much lower than CAC in aqueous PEO homopolymer solutions.

Adsorption of sodium cyclododecylmethanoate and cycloundecylmethanoate at the air/water interface

1984 ◽  
Vol 62 (11) ◽  
pp. 2359-2363 ◽  
Author(s):  
Jan J. Spitzer
Keyword(s):  
Aqueous Solutions ◽  
Sodium Ion ◽  
Ion Concentration ◽  
Ionic Surfactants ◽  
Free Energies ◽  
Straight Chain ◽  
Double Chain ◽  
Adsorbed State ◽  
Critical Micelle Concentrations ◽  
Air Water Interface

Surface tension measurements on aqueous solutions of sodium cyclododecylmethanoate and sodium cycloundecylmethanoate in sodium carbonate/bicarbonate buffers and at constant sodium ion concentration at 25 °C were used to obtain the standard free energies of adsorption, the saturation areas per surfactant ion, and the critical "micelle" concentrations of these compounds. Similar measurements were done for solutions of sodium dodecanoate for comparisons.The standard free energies of adsorption of CH2 group that is located in a macrocyclic cycloalkyl ring appears to follow the "rule of two" (−RT ln 2) that is also valid for straight chain ionic surfactants. The saturation areas of both cyclododecylmethanoate and cycloundecylmethanoate are about 52 Å2/ion as compared to about 32 Å2/ion for normal dodecanoate.For large ring cycloalkylmethanoates the critical "micelle" concentrations appear to decrease by a factor of about 4/5 for each CH2 group added to the ring as compared to the factor of about 1/2 for each CH2 group added to the chain of normal alkanoates. The data suggest that large cycloalkyl rings have "collapsed ring", or "double chain", conformation in aqueous solutions and in the adsorbed state.

scholarly journals PECULARITIES OF MICELLE FORMATION OF PENTACYCLIC GLYCOSIDES IN AQUEOUS SOLUTIONS

2021 ◽  
Vol 64 (4) ◽  
pp. 26-33
Author(s):  
Natalia V. Mironenko ◽  
Irina V. Shkutina ◽  
Vladimir F. Selemenev
Keyword(s):  
Surface Tension ◽  
Light Scattering ◽  
Dynamic Light Scattering ◽  
Aqueous Solutions ◽  
Hydrodynamic Radius ◽  
Critical Concentration ◽  
Micelle Formation ◽  
Cylindrical Shape ◽  
Scattering Method ◽  
Dynamic Light Scattering Method

The regularities of changes in structural characteristics during the formation of associates in micellar aqueous solutions of triterpene saponins Quillaja Saponin and Sapindus Mukorossi are considered. The dependence of surface tension and adsorption on the concentration of an aqueous saponin solution is analyzed, and the values of surface activity and parameters of the adsorption layer are calculated. The average values of diffusion coefficients for spherical and cylindrical micelles are determined based on the measurement of the solution viscosity. The effect of the electrolyte solution on the surface tension and viscosity of glycoside solutions is studied: when the electrolyte is introduced into the saponin solution, the surface tension decreases, which leads to a shift in the critical concentration of micelle formation towards lower concentrations. The introduction of potassium chloride electrolyte reduces the degree of ionization and, as a result of suppressing the electroviscosity effect, leads to a decrease in the viscosity of the solution. The dynamic light scattering method is used to determine the size of glycoside aggregates. It is established that there are aggregates of several sizes in an aqueous solution of saponin. The size and shape of aggregates were calculated using the concepts of micelle packing parameters. In the region of very low concentrations of glycoside solutions, when approaching the critical concentration of micelle formation in the solution, there are spherical micelles. A further increase in the saponin concentration in the solution leads to a decrease in the content of structures with a hydrodynamic radius of 50-80 nm and the appearance of larger agglomerates with sizes greater than 100 nm. It was found that micelles acquire a less hydrated and more densely packed cylindrical shape in the concentration range of 1.7-2.6 mmol/dm3. Compaction of associates leads to an increase in the content of particles with a hydrodynamic radius of 150-250 nm and larger ones, and their presence predicts the appearance of larger agglomerates. Analyzing the data obtained using the dynamic light scattering method, it can be concluded that aggregates of several sizes co-exist in the volume of aqueous saponin solutions at certain concentrations.

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