What is critical micelle concentration of surfactant and its significance?
The CMC (critical micelle concentration) is the concentration of a surfactant in a bulk phase, above which aggregates of surfactant molecules, so-called micelles, start to form. The CMC is an important characteristic for surfactants.
How is surfactant concentration measured?
The surface tension of a sample with an unknown surfactant concentration is measured in Online-Mode or in Single-Mode using the determined bubble lifetime (30 ms). Based on the reference curve the corresponding surfactant concentration is assigned to the measured surface tension (influence of surface active agents).
What is the meaning of critical micelle concentration?
Critical micelle concentration (CMC) can be defined as the minimum concentration of the surfactant at which micelle formation takes place. From: Comprehensive Nanoscience and Nanotechnology (Second Edition), 2019.
What is the significance of critical micelle concentration?
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. The CMC is an important characteristic of a surfactant.
What happens at critical micelle concentration?
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.
Why surfactants form micelles?
Surfactants absorb at interfaces The cohesive forces between the water molecules are very strong making the surface tension of water high. As surfactants absorb they break these interactions. When the surfactant concentration is high, they form micelles.
What is the CMC of SDS surfactant?
Sodium dodecylsulfate (SDS) is a typical anionic surfactant that has a critical micellar concentration (cmc) around (8 . 2 × 10 − 3 ) mol-L − 1 at 25 ◦ C in the absence of any other additive.
How do surfactants form micelles?
What is the use of critical micelle concentration?
The critical micelle concentration (CMC) determines whether or not a detergent can be easily removed (Hasler et al., 1998).
Why does surfactant form micelles?
The intermolecular forces between surfactant and water molecule are much lower than between two water molecules and thus surface tension will decrease. When the surfactant concentration is high, they form micelles.
Which is a characteristic of the critical micelle concentration?
Another important characteristic is the critical micelle concentration (CMC), which is defined as the concentration of surfactants when the micelles spontaneously form. The addition of surfactant reduces the interface energy and removes the hydrophobic groups of the surfactant from contact with water (Fig. 4.18A).
What happens when the concentration of a surfactant reaches CMC?
Upon reaching CMC, any further addition of surfactants will just increase the number of micelles (in the ideal case), as shown in Figure 7.1. In other words, before reaching the CMC, the surface tension decreases sharply with the concentration of the surfactant.
How does the CMC affect the formation of micelles?
The increasing concentration of surfactant above the CMC results in more formation of micelles but hardly reduces the free energy of the system. Another factor to be related to CMC is Krafft temperature or critical micelle temperature, which is defined as a minimum temperature where surfactants can form micelles.
How does nonionic surfactant affect the formation of micelles?
Below the Krafft temperature condition, no micelles form regardless of the concentration of surfactant. The cloud point is another parameter to illustrate the behavior of nonionic surfactant. It is defined as the temperature, at which the phase separation is observed and the solution becomes cloudy.