Back Kritická micelární koncentrace Czech Kritisk micellekoncentration Danish Kritische Mizellbildungskonzentration German Concentración micelar crítica Spanish Concentration micellaire critique French ריכוז המיצלה הקריטי HE CMC-érték Hungarian Concentrazione micellare critica Italian 臨界ミセル濃度 Japanese Concentrazion micellara critega LMO
In colloidal and surface chemistry, the critical micelle concentration (CMC) is defined as the concentration of surfactants above which micelles form and all additional surfactants added to the system will form micelles.[1]
The CMC is an important characteristic of a surfactant. Before reaching the CMC, the surface tension changes strongly with the concentration of the surfactant. After reaching the CMC, the surface tension remains relatively constant or changes with a lower slope. The value of the CMC for a given dispersant in a given medium depends on temperature, pressure, and (sometimes strongly) on the presence and concentration of other surface active substances and electrolytes. Micelles only form above critical micelle temperature.
For example, the value of CMC for sodium dodecyl sulfate in water (without other additives or salts) at 25 °C, atmospheric pressure, is 8x10−3 mol/L.[2]
| Surfactant | CMC (molarity) | Category |
|---|---|---|
| Sodium octyl sulfate | 0.13 | anionic surfactant |
| Sodium dodecyl sulfate | 0.0083 | anionic surfactant |
| Sodium tetradecyl sulfate | 0.0021 | anionic surfactant |
| Decyltrimethylammonium bromide | 0.065 | cationic surfactant |
| Dodecyltrimethylammonium bromide | 0.016 | cationic surfactant |
| Hexadecyltrimethylammonium bromide | 0.00092 | cationic surfactant |
| Penta(ethyleneglycol)monooctyl ether | 0.0009 | neutral surfactant |
| Penta(ethyleneglycol)monodecyl ether | 0.0009 | neutral surfactant |
| Pentaethylene glycol monododecyl ether | 0.000065 | neutral surfactant |
- ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "critical micelle concentration". doi:10.1351/goldbook.C01395
- ^ Dominguez, Ana; Fernandez, Aurora; Gonzalez, Noemi; Iglesias, Emilia; Montenegro, Luis (October 1997). "Determination of Critical Micelle Concentration of Some Surfactants by Three Techniques". Journal of Chemical Education. 74 (10): 1227–1231. doi:10.1021/ed074p1227. ISSN 0021-9584. Archived from the original on 13 March 2023. Retrieved 2 June 2023.
- ^ Holmberg, Krister (2019). "Surfactants". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. pp. 1–56. doi:10.1002/14356007.a25_747.pub2. ISBN 9783527306732. S2CID 242339510.