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Electrolyte effect on lamellar domain morphology in a nonionic surfactant solution below the Krafft temperature
Youhei Kawabata1, Akira Murakami, Tadashi Kato
1Department of Chemistry, Tokyo Metropolitan University , Hachioji, Tokyo 192-0397, Japan.
The Journal of Physical Chemistry. B
|January 10, 2014
Summary
Adding specific ions to nonionic surfactant solutions alters their structure. Chaotropic ions transform vesicles to networks, while kosmotropic ions like sodium thiocyanate (NaSCN) induce cylinder-like structures in C16E6 surfactant solutions.
Area of Science:
- Physical Chemistry
- Materials Science
- Colloid and Surface Chemistry
Background:
- Previous studies investigated lamellar domain morphology in nonionic surfactants C16E6 and C16E7 below the Krafft temperature.
- Understanding electrolyte effects on surfactant morphology is crucial for various applications.
Purpose of the Study:
- To investigate the impact of electrolytes on the lamellar domain morphology of nonionic surfactants C16E6 and C16E7.
- To elucidate the mechanism behind the formation of cylinder-like structures induced by sodium thiocyanate (NaSCN).
Main Methods:
- Differential Scanning Calorimetry (DSC)
- Confocal Microscopy
- Small-Angle X-ray Scattering (SAXS)
- Wide-Angle X-ray Scattering (WAXS)
Main Results:
- Chaotropic ions (Cl-, F-, CH3COO-) transformed vesicles in C16E7 solutions into network structures.
- Kosmotropic ions (SCN-) induced a transition from network structures to vesicles in C16E6 solutions.
- Specific concentrations of NaSCN led to the formation of unique cylinder-like domains in C16E6 solutions, accompanied by anomalous swelling of lamellar structures.
Conclusions:
- Electrolytes significantly influence nonionic surfactant morphology, offering pathways to control self-assembly.
- The formation of cylindrical vesicles in the C16E6/NaSCN system is attributed to osmotic pressure differences induced by NaSCN addition.
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