Self-assembly of mixed surfactants sodium dodecylsulfate and polyethylene glycol dodecyl ether in aqueous solutions
Journal of Molecular Liquids, 412 (2024) 125742 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 interf...
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| Main Authors: | , , , |
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| Format: | Journal Article |
| Language: | English |
| Published: |
02-10-2024
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Journal of Molecular Liquids, 412 (2024) 125742 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. |
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| DOI: | 10.48550/arxiv.2410.01983 |