Surfactants are used in many industrial fields as detergents, wetting agents, emulsifiers, foaming agents, and dispersants. Characterization of surfactants is thus important to optimize their performance and the products they are applied to. Surface and interfacial tension measurements offer one of the most versatile methods to study the properties and behavior of the surfactant solutions. '
To what value surfactant is able to reduce surface or interfacial tension?
The main purpose of the surfactant is to reduce the surface and interfacial tension. To study to what extent a surfactant is able to do that, surface and interfacial tension measurements are needed. With the same measurement, it is also possible to study the kinetics of the surfactant as the surface and interfacial tension can be measured as a function of time.
What is the optimum amount of surfactant?
In addition to surface and interfacial tension measurements, critical micelle concentration (CMC) measurements are utilized to determine the optimum amount of surfactant in a solution. The surface tension of the surfactant solution doesn't decrease any longer after the CMC point is reached. Thus, it is commonly used as an indicator of the amount of surfactant needed in a formulation.
How stable is the surfactant film?
Surface and interfacial tension measurements can also be used to study the stability of the surfactant film at the interface. This is needed especially in emulsions where two phases, typically oil and water, are mixed together. The stability of the film is important as more stable the film, better it is able to hinder e.g. the coalescence of the oil droplet. The stability of the film can be studied by pulsating the drop at the certain frequency and following the change in interfacial tension.
For more information on how to choose the method to characterize your surfactant solution, please read the white paper below.
A term surfactant comes from the word surface active agent. At the interface, they align themselves so that the hydrophobic part is in the air and hydrophilic part is in water. This will cause the decrease in surface or interfacial tensions.