These materials are available in the market in anionic, non-ionic and cationic types, and due to their unique properties, they are used in various industries such as detergents, agriculture, etc. In Persian, these compounds are also known as surfactants.
What is surfactant?
There are substances that reduce the surface tension between two liquids or between a liquid and a solid. In general, any substance that affects surface tension can be considered a surfactant, but they may also act as wetting agents, emulsifiers, foaming agents, and dispersants. Surface activators play an important role in cleaning, wetting, dispersing, emulsifying, foaming and antifoaming in many industries and products.
These products include paints, emulsion adhesives, ink, disinfectants, shampoos, toothpaste, fire extinguishers, detergents, insecticides, cleaning recycled paper, etc.
Attributes
In the aqueous phase, these materials form compounds called micelles, and the hydrophobic tails form the core, and the hydrophilic heads are immersed around the liquid. In addition to this, other structures can be produced. The types of these structures are spherical micelles or lipid layers.
Anionic surfactant
The shape of the molecules depends on the size balance between the hydrophilic head and the hydrophobic tail. The measure of this balance is HLB, hydrophilic-lipophilic. Surfactants above HLB > 10 are hydrophilic (“water-loving”) and are in the form of O/W (oil in water) emulsions.
Lipophilic surfactants have low values (HLB (1-10) and are in the form of W / O (water in oil) emulsion. Note that (SLS = sodium lauryl sulfate) are surfactants with a high level of HLB
As mentioned before, the structure of surfactants consists of tail and head. The “tail” of most surfactants is almost similar and consists of a hydrocarbon chain that can be branched, linear or aromatic.
Fluorosurfactants have fluorocarbon chains. The type of siloxane has siloxane chains. Today, with the progress of science, more different structures of this compound have been published.
The non-ionic type does not have any charge in its head, but the ionic type has a charge. If the charge is negative, the surfactant is specifically called anionic. If the charge is positive, it is called a cation. If it contains two oppositely charged groups, it is called amphoteric.