Secondary Surfactants for Personal Care Applications

Primary surfactants, most commonly anionic in nature, carry a negative charge on the surface active or hydrophobic portion of the molecule (RCOO– Na+, where R is a fatty hydrophobe). “Surfactant” denotes an organic molecule having surfaceactive properties. The term surfactant is a convenient contraction of “surface active agent,” that originated in one of the industry’s leading laboratories and is now widely accepted. Secondary surfactants can be loosely defined as any surface-active agent that is used in conjunction with a primary surfactant to enhance foaming characteristics, modify formulated viscosity responses, or improve the overall mildness of the formulation. It can also be employed as a wetting agent, a solubilizer of essential oils and fragrances, or a conditioner for hair and skin. In the personal care world, primary surfactants are generally anionic in nature. Thus, for the purpose of this discussion, amphoterics, and non-ionics will be treated as secondary surfactants. The main focus of this chapter is the application of these surfactants in the personal care arena, with some emphasis on the synthesis process as well as chemical and physical properties.