groups from a spacer group of various nature: hydrophilic or hydrophobic, rigid or flexible. These surfactants represent a new class of surfactants that is making its way into surfactant-based formulations. Dimeric surfactants represent a new class of surfactants. They consist of two amphiphilic portions connected at the heads or very close to the heads by a spacer group.4-octylphenol polyethoxylate (Triton of surfactant. 10 they act as in aqueous systems due to their nature/structure and the nature/structure of water Once a surfactant monomer is added to water, the water forms a “cage” around the hydrophobic carbon chain from which it is formed. driven the strength of the hydrogen bonds between the water molecules, leading to the loss of entropy of the water molecules. It is this loss of entropy rather than the bond energy that leads to an unfavorable free energy change for the one-time process. added to a system, before equilibrium is reached between the surfactant monomers at the interface and those in the bulk, the surfactants become concentrated at the interfaces, where they gradually decrease the overall free energy or surface tension of the system. Their orientation on the interface varies depending on the system components. At the water/air interface, the head group is buried in the solution while the tail group extends out of the solution. At the oil/air interface, the tail group is buried i...... in the center of the paper ...... the mechanism of ionic surfactants differs from that of non-ionic surfactants. The pattern of a typical surfactant adsorption isotherm frequently seen for The adsorption of ionic surfactants on oppositely charged surfaces is commonly divided into four regions,9, 10. The shape of a typical nonionic surfactant adsorption isotherm follows the Langmuir equation. Unlike ionic surfactants, the adsorption isotherms of nonionic surfactants have no clear transition points. At very low concentrations, non-ionic surfactant monomers are adsorbed via Admicelles Hemimicelles Micelles (formed in solution) Reverse Micelles14hydrogen bonding between the substrate and hydrophilic groups. The amount of adsorbed surfactant increases slowly with increasing equilibrium concentration in the bulk phase. After the CHC or CAC, the slope of the isotherm increases up to the CMC and then flattens.8