3. Classification by molecular configuration

The above discussion is limited to the case where the hydrophilic/hydrophobic part of the surfactant has a single structure. With the continuous update of the structure of surfactants, both the hydrophilic head group and the hydrophobic tail chain have diversified combinations. As for the hydrophilic head group, for example, fatty alcohol polyoxyethylene (3) sulfosuccinate monoester disodium (MES) contains polyoxyethylene, sulfonate and carboxylate groups; alcohol ether phosphate (AEP) contains polyoxyethylene (AEO) and phosphate groups, etc.