Knowra Critical micelle concentration Critical micelle concentration The critical micelle concentration (CMC) is the surfactant concentration above which micelles form in appreciable amounts. Above it, added surfactant increasingly enters micelles rather than raising the free-molecule concentration.
Micelle : A self-assembled aggregate of surfactant molecules, typically with hydrophobic regions shielded from water. Micelles are the aggregates whose appreciable formation defines the CMC.
Amphiphile : A molecule or material with distinct regions that interact differently with polar and nonpolar environments. Surfactants are amphiphiles, and their dual affinity drives micellization.
Detergency : The removal of soil from a surface, commonly through surfactant-assisted wetting, dispersion, and solubilization. Surfactant levels relative to the CMC affect how efficiently oily soils are solubilized.
Solubilization : The process of increasing a substance's apparent solubility in a liquid, often by incorporating it into aggregates. Above the CMC, micelles can incorporate hydrophobic compounds and increase their apparent aqueous solubility.
Surfactant : A substance that lowers surface or interfacial tension, usually through molecules with hydrophilic and hydrophobic regions. Surfactant molecules are the material whose concentration is increased toward the threshold.
Hydrophobic effect : The tendency of nonpolar substances to associate in water, reducing disruption of water's hydrogen-bond network. This effect helps drive surfactant tails to cluster inside micelles.
Microemulsion : A thermodynamically stable, isotropic mixture of oil, water, and surfactant, often with a cosurfactant. Micellization and related aggregation help determine how surfactants stabilize oil–water mixtures.
Surface excess : The excess amount of a component at an interface relative to its bulk concentration. Surfactant adsorption at interfaces approaches saturation around micelle formation.
Critical aggregation concentration : The concentration above which amphiphilic molecules begin forming aggregates, including structures other than conventional micelles. It generalizes the threshold idea when surfactants form non-micellar aggregates.
Hydrophilic-lipophilic balance : A numerical classification of surfactants based on the relative strength of their hydrophilic and lipophilic portions. The balance between head and tail influences whether micelles form and at what concentration.
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