surfactants are molecules which they can lower surface tension and also form "micelle" structure. alcohols also can lower surface tension but they cannot form micelles (does any exception exist? ). then assume that in a specific solution, there are alcohols and surfactans simultaneously, what are the micelle formation conditions? i mean effect of alcohlol and surfactant concentrations, thermodynamic parameters. and does these parameters affect the micelles structure? and what is effect of presence of alcohol, on cloud point of nonionic surfactant,?
Alcohols C1-C4 dissolve in water well. Up to a certain concentration, for example, C2 0.099, the mole fraction of the alcohol forms in the water heterophase fluctuations or fluctuations in the density of water. Such solutions enhance the hydrophobic interaction of the surfactant or reduce the CMC. Alcohols larger than C5 are solubilized in micelles. Their dissolution in water can be neglected.
See the file of our article.Polymorphic transitions in n-hydrocarbon-water and n-alcohol-water binary systems.
I can see you are a bit confused Mohammad;
The reason why surfactants form a micelle is their hydrophobic part of their structure. The more they are hydrophobic (longer chain, smaller head), the lower the concentration they form the micelle. Simply because they are fleeing from water, so they gather around each other to be in "less stressed" or lets say lowest energy level and they form micelles.
On the other hand, alcohols mix with water very well as they are polar liquids and the electrostatic interaction helps them to dissolve in water in any concentration. So they dont have any problem being around the water molecules. So we wont see any micelle formation for alcohols (there is no fear and stress)!
Lets take a look at the water+alcohol+surfactant system now. Presence of the alcohol in water, decreases the surface tension of water, so the surfactants dont feel as much stress as they feel in pure water, then they dont tend to form micelles in lower concentrations. Then we say, the CMC moves towards the higher concentration when we add alcohol to water.
If you have a very oily surfactant with very low HLB, you cannot solve it in water, but if you add some alcohol, the surfactant will dissolve in water+alcohol system.
Take a look at some papers related to HLB of surfactants. That should help...
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