Kinetics and Mechanism of Cationic Micelle/Flexible Nanoparticle Catalysis: A Review

Thermodynamics of the micellization of quaternary based cationic surfactants in triethanolamine-water media: a conductometry study

The effect of triethanolamine, a solvent with wide technical and industrial benefit on the micellization of an aqueous mixture of cationic surfactants, dodecyltrimethylammonium bromide (DETAB) and hexadecyltrimethylammonium bromide (HATAB) was studied to examining the stability of the mixed micelles at 298.1, 303.1, 308.1 and 313.1 K using the electrical conductance method. The values of the critical micelle concentration (C*) were found to decrease with an increase in the concentration of triethanolamine (TEA). The values of the free energy of micellization (ΔGm) were negative at a particular temperature, and the extent of spontaneity was discovered to increase when the concentration of TEA was increased. However, an increase in temperature was observed to have a negative linear relationship with the spontaneity of the process. The formation of the mixed micelles was an exothermic process, and it was also TEA and temperature-dependent with a trend similar to those observed in the free energy of micellization (ΔGm). The degree of disorderliness of the system was also found to be entropy driven at a higher concentration of TEA. The synergistic interaction between the molecules of DETAB–HATAB in the presence of TEA (0.4% v/v) and the spontaneity of the system was at the maximum at 0.1:0.9 mol fraction ratio and the energetics of the system was discussed based on hydrophobic–solvophobic interaction of the monomers in TEA at elevated temperatures.

Recent advances on micellar catalysis in water

Water is the universal solvent in nature to catalyze the biological transformation processes. However, owing to the immiscibility of many reagents in water, synthesis chemistry relies heavily on organic solvent. Micellar media is a green alternative to traditional petroleum feedstock derived solvents, which is recently attracting increasing research attention. The present review deals with the recent advances in micellar catalysis with an emphasis on the new "tailor-made" surfactants for various reactions. A brief overview of commercial surfactants, including anionic micelles, cationic micelles, and nonionic micelles is presented. More importantly, an attempt was made to discuss systematically the recent research progress on new surfactants by introducing structures, micellar effects and recycling process, aiming to serve as the basis for future development of surfactants.