Temperature Comparative Studies on Self‐Assembly of Sodium Dodecyl Sulphate and Didodecyl Dimethyl Ammonium Bromide in Aqueous, Brine, and Trifluoroethanol Media

Abstract

An approach based on experimental and theoretical methods was used to compare the self-assembly [i.e., determination of the critical micelle concentration (CMC), degree of ionization (α) and counterion binding (β)] of sodium dodecyl sulfate (SDS) and didodecyl dimethyl ammonium bromide (DDAB) in deionized water and 10 mM NaCl and 10 (vol) % trifluoroethanol solutions. Experimental methods consisted of electrical conductometry, tensiometry, fluorimetry, and determination of Krafft temperature. A critical analysis of the thermodynamics of self-assembly by the Gibbs-Helmholtz equation and the van't-Hoff rationale provided values of several parameters, such as the change of Gibbs free energy and enthalpy change of micellization (ΔG 0 m and ΔH 0 m , respectively) and the Gibbs free energy of surfactant tail groups (ΔG 0 trans ). Interfacial properties, aggregation number (N agg ), micropolarity (I 1 /I 3 ), microviscosity (η), packing parameter (P), dielectric constant (D), anisotropy (r), and Stern-Volmer binding constant (K SV ) for SDS and DDAB in different temperatures and different systems were determined.

Improved Core Viscosity Achieved by PDLLA10kCo-Incorporation Promoted Drug Loading and Stability of mPEG2k-b-PDLLA2.4k Micelles

“…The thermodynamic stability of micelles can be characterized by the critical aggregation concentration (CAC), i.e., the minimum concentration at which the polymer self-assembles to micelles. Compared to the higher CAC of small molecule surfactants, the CAC of block copolymers is three orders of magnitude lower, representing higher thermodynamic stability (32,33). In this paper, the CAC of micelles gradually decreased with the increase of PDLLA 10k incorporation.…”

Effect of Spacer Structures on the Interfacial Adsorption and Micelle Properties of Quaternary Ammonium Salt-Based Gemini Surfactants

“…Clear aqueous solutions of quaternary ammonium salt-based gemini surfactants (0.0050–0.20 wt %) were prepared and placed in a refrigerator at ∼5 °C for at least 24 h. As the solutions were clear with no visible precipitates, the T K value was estimated to be <5 °C. As the gemini surfactants precipitated out from the solutions, the temperature of the cooled surfactant solutions was raised gradually under constant stirring, and the conductance (κ) was measured by raising the temperature from 0.5 to 5.0 °C. ,, The conductivity of the surfactant solution increased with increasing temperature due to dissolution of the surfactants. The conductivity increased gradually above a certain temperature.…”

“…As the gemini surfactants precipitated out from the solutions, the temperature of the cooled surfactant solutions was raised gradually under constant stirring, and the conductance (κ) was measured by raising the temperature from 0.5 to 5.0 °C. 27,31,32 The conductivity of the surfactant solution increased with increasing temperature due to dissolution of the surfactants. The conductivity increased gradually above a certain temperature.…”

Refined definition of the critical micelle concentration and application to alkyl maltosides used in membrane protein research

“…These interactions are a direct function of the detergent's molecular structure, which in a molecular thermodynamic model can be linked to the free energy difference between the detergent monomer and the micelle. 3,[11][12][13][14][15][16] A quantity of particular interest is the critical micelle concentration (CMC), which is the total detergent concentration that must be exceeded for micellar structures to be formed in the solution [11][12][13][14] and for hydrophobic substances or membrane proteins to be solubilized. 17 In our earlier work, 3 we investigated the inuence of poly(ethylene glycol) (PEG), a common precipitant used to induce protein crystallization, on the CMC of alkyl maltosides in order to better understand the detergent behavior under the conditions of membrane protein crystallization.…”

“…These interactions are a direct function of the detergent's molecular structure, which in a molecular thermodynamic model can be linked to the free energy difference between the detergent monomer and the micelle. 3,11–16 A quantity of particular interest is the critical micelle concentration (CMC), which is the total detergent concentration that must be exceeded for micellar structures to be formed in the solution 11–14 and for hydrophobic substances or membrane proteins to be solubilized. 17…”