Reversible Switching of a Micelle‐to‐Vesicle Transition by Compressed CO₂

Abstract

The study of the micelle-to-vesicle transition (MVT) is of great importance from both theoretical and practical points of view. Herein, we studied the effect of compressed CO(2) on the aggregation behavior of dodecyltrimethylammonium bromide (DTAB)/sodium dodecyl sulfate (SDS) mixed surfactants in aqueous solution by means of direct observation, turbidity and conductivity measurements, steady-state fluorescence, time-resolved fluorescence quenching (TRFQ), fluorescence quantum yield, and template methods. Interestingly, all these approaches showed that compressed CO(2) could induce the MVT in the surfactant system, and the vesicles returned to the micelles simply by depressurization; that is, CO(2) can be used to switch the MVT reversibly by controlling pressure. Some other gases, such as methane, ethylene, and ethane, could also induce the MVT of the surfactant solution. A possible mechanism is proposed on the basis of the packing-parameter theory and thermodynamic principles. It is shown that the mechanism of the MVT induced by a nonpolar gas is different from the MVT induced by polar and electrolyte additives.

CO2-responsive TX-100 emulsion for selective synthesis of 1D or 3D gold

“…Application of this principle has been studied in controlling the properties of different surfactant assemblies, such as reverse micelles, 18-20 micelles, 21 vesicles, 22 and switching phase transition between them. 23,24 In a previous paper, we found that CO 2 is also efficient in tuning the properties of an emulsion system, which is stabilized by a anionic surfactant of bis-2-ethylhexylsulfosuccinate (AOT). 25 In comparison with the conventional methods to tune the properties of surfactant systems (adding solid or liquid additives), the use of CO 2 has many advantages.…”

Supramolecular Assemblies of Amphiphilic L‐Proline Regulated by Compressed CO2 as a Recyclable Organocatalyst for the Asymmetric Aldol Reaction

“…In recent years, with the progress in sustainable chemistry, supercritical or compressed CO 2 has been widely used in many aspects. [11] Compressed CO 2 can trigger the formation of nanoemulsions reversibly, [12] and switch the micelle-tovesicle transition (MVT) [13] and the liquid-crystal-to-micelle transition. [14] Furthermore, by regulating the pressure, compressed CO 2 favors the separation of the products.…”

Supramolecular Assemblies of Amphiphilic L‐Proline Regulated by Compressed CO2 as a Recyclable Organocatalyst for the Asymmetric Aldol Reaction

“…In recent years, with the progress in sustainable chemistry, supercritical or compressed CO 2 has been widely used in many aspects 11. Compressed CO 2 can trigger the formation of nanoemulsions reversibly,12 and switch the micelle‐to‐vesicle transition (MVT)13 and the liquid‐crystal‐to‐micelle transition 14. Furthermore, by regulating the pressure, compressed CO 2 favors the separation of the products 15.…”