Understanding Surfactants And New Methods Of Dispersing Them

By Christine Angos
Application Engineer
Charles Ross & Son Company

Surface-active agents, or surfactants for short, are compounds that lower the surface tension of a liquid and lower the interfacial tension between two liquids. Surfactants are amphiphilic in nature, possessing both hydrophilic (affinity for water or aqueous phases) and lipophilic (affinity for oily or organic phases) properties. The unique combination of these opposing properties in the same molecule is what enables a surfactant to reduce surface and interfacial tensions.

When present in high concentrations — above what is known as critical micelle concentration, or CMC — surfactant molecules will assemble in the bulk solution and form aggregates known as micelles. This tendency to orient at surfaces and form micelles allows surfactants to perform a number of basic functions.

Surfactants act as foaming agents, emulsifiers, and dispersants, suspending gases, immiscible liquids, or solids, respectively, in water or some other liquid. Solubilization, a function closely related to emulsification, is a condition where suspended droplets and surfactant micelles are of the same size. Finally, detergency is a complex combination of all the previous functions. Surfactants suspend, solubilize, dissolve, and separate soil from a surface being cleaned.