Self-assembly of mixed surfactants sodium dodecylsulfate and polyethylene glycol dodecyl ether in aqueous solutions

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Main Authors: Teixeira, Juliano F., Quintão, Juliana Silva, Oliveira, Kairon M., Teixeira, Alvaro V. N. C.
Format: Preprint
Published: 2024
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author Teixeira, Juliano F.
Quintão, Juliana Silva
Oliveira, Kairon M.
Teixeira, Alvaro V. N. C.
author_facet Teixeira, Juliano F.
Quintão, Juliana Silva
Oliveira, Kairon M.
Teixeira, Alvaro V. N. C.
contents The thermodynamic behavior of mixed systems containing the anionic surfactant sodium dodecyl sulfate (SDS) and the nonionic surfactant polyethylene glycol dodecyl ether (Brij L4) in aqueous solutions was investigated. Electrical conductivity and interfacial tension measurements were employed to investigate the concentration-dependent properties of these surfactant mixtures. Two main experiments were conducted: i) constant ratio experiment: the overall surfactant concentration was varied while maintaining a fixed ratio between SDS and Brij L4. It was shown that the critical micelle concentration (CMC) determined from electrical conductivity measurements does not indicate the formation of the first mixed micelles as observed using tensiometry, but the point from which the adsorption of counterions by the existing micelles became important. By using the Regular Solution Theory (RST), it was found that the interaction between SDS and Brij L4 is synergistic, driven by dipole-ion interactions of the hydrophilic regions of the two surfactants. ii) Fixed SDS concentration while increase the Brij L4 concentration: the resulting electrical conductivity exhibited non-trivial behavior which complexity arose from simultaneous phenomena of incorporation of free SDS molecules into the micelles as Brij L4 concentration increased, leading to a decrease in electrical conductivity; liberation of some adsorbed counterions from the mixed micelles to the solution, which increases the conductivity and increase of viscosity due to Brij L4 further addition that leads to a sequential decrease in electrical conductivity.
format Preprint
id arxiv_https___arxiv_org_abs_2410_01983
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Self-assembly of mixed surfactants sodium dodecylsulfate and polyethylene glycol dodecyl ether in aqueous solutions
Teixeira, Juliano F.
Quintão, Juliana Silva
Oliveira, Kairon M.
Teixeira, Alvaro V. N. C.
Soft Condensed Matter
Materials Science
The thermodynamic behavior of mixed systems containing the anionic surfactant sodium dodecyl sulfate (SDS) and the nonionic surfactant polyethylene glycol dodecyl ether (Brij L4) in aqueous solutions was investigated. Electrical conductivity and interfacial tension measurements were employed to investigate the concentration-dependent properties of these surfactant mixtures. Two main experiments were conducted: i) constant ratio experiment: the overall surfactant concentration was varied while maintaining a fixed ratio between SDS and Brij L4. It was shown that the critical micelle concentration (CMC) determined from electrical conductivity measurements does not indicate the formation of the first mixed micelles as observed using tensiometry, but the point from which the adsorption of counterions by the existing micelles became important. By using the Regular Solution Theory (RST), it was found that the interaction between SDS and Brij L4 is synergistic, driven by dipole-ion interactions of the hydrophilic regions of the two surfactants. ii) Fixed SDS concentration while increase the Brij L4 concentration: the resulting electrical conductivity exhibited non-trivial behavior which complexity arose from simultaneous phenomena of incorporation of free SDS molecules into the micelles as Brij L4 concentration increased, leading to a decrease in electrical conductivity; liberation of some adsorbed counterions from the mixed micelles to the solution, which increases the conductivity and increase of viscosity due to Brij L4 further addition that leads to a sequential decrease in electrical conductivity.
title Self-assembly of mixed surfactants sodium dodecylsulfate and polyethylene glycol dodecyl ether in aqueous solutions
topic Soft Condensed Matter
Materials Science
url https://arxiv.org/abs/2410.01983