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Phase Behavior of Charged Vesicles Under Symmetric and Asymmetric Solution Conditions Monitored with Fluorescence Microscopy
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Reversible phase transition from vesicles to lamellar network structures triggered by chain melting
Yuwen Shen1, Jingcheng Hao1, Heinz Hoffmann2
1Key Laboratory of Colloid and Interface Chemistry (Shandong University), Ministry of Education, Jinan, 250100, P. R. China. jhao@sdu.edu.cn.
Soft Matter
|September 10, 2020
Summary
Chain melting in catanionic surfactant vesicles triggers a reversible structural transition to network structures. This phase conversion, influenced by salt concentration, offers insights into vesicle fusion and fluctuation dynamics.
Area of Science:
- Materials Science
- Physical Chemistry
- Supramolecular Chemistry
Background:
- Catanionic surfactant vesicles, formed from cationic and anionic surfactants, exhibit complex phase behavior in aqueous solutions.
- Understanding the structural transitions of these vesicles is crucial for applications in drug delivery and materials science.
Purpose of the Study:
- To investigate the reversible phase structural transition of catanionic tetradecyltrimethylammonium laurate (TTAL) vesicles.
- To elucidate the role of chain melting and salt concentration in this transition.
- To characterize the transformation from vesicles to network structures.
Main Methods:
- Fourier transform infrared (FT-IR) spectroscopy to monitor chain melting.
- Turbidity and viscosity measurements to track the phase transition.
- Transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) to visualize structural changes.
Main Results:
- A reversible phase structural transition from vesicles to extended bilayer networks was observed upon chain melting.
- The transition temperature (Tm) was dependent on salt (NaBr) concentration but not on dilution.
- The conversion process was progressive and linked to enhanced membrane elasticity and altered surfactant interactions.
Conclusions:
- Chain melting is a key trigger for the vesicle-to-network structural conversion in catanionic TTAL systems.
- Salt concentration significantly influences the phase transition temperature.
- This observed phase conversion provides valuable insights into vesicle fusion, fission, and fluctuation mechanisms.
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