Surfactants serve several key functions in cosmetics. They can increase the solubility of insoluble substances, allowing ingredients like oils and fragrances to be incorporated into lotions. Surfactants also enable the creation of emulsions through emulsification, allowing oils and water to combine in creams. Through dispersion, surfactants help non-aqueous substances to be uniformly suspended in water-based cosmetic products. Different types of surfactants provide cleansing, conditioning, softening, and moisturizing effects important for products like shampoos, cleansers, and conditioners.

1. The Function of Surfactants in Cosmetics
Solubilization
The effect of increasing the solubility of a sparingly soluble or insoluble substance is referred to
as solubilization. In cosmetics, solubilizers are mainly used in the production of lotions, hair oils,
and hair conditioners. Due to the difference in structure and polarity of oily ingredients such as
perfumes, oils and oil-soluble vitamins in cosmetics, their solubilizers are also different. For
example, the solubilizing object of the lotion is a fragrance, an oil, a chemical, etc., and thus the
solubilizing agent may be alkyl polyoxyethylene ether. In addition, castor oil-based amphoteric
derivatives have excellent solubility for perfume oils and vegetable oils, and such surfactants are
non-irritating to the eyes, so they are suitable for the preparation of non-irritating shampoos.
Emulsification
The phenomenon in which the water-insoluble substance is emulsified in water to form an
emulsion is called emulsification. Emulsifiers are mainly used in cosmetics to produce creams and
lotions. Common vanishing creams are O/W emulsions. Due to the low irritation of nonionic
emulsifiers, they are currently the most widely used emulsifiers.
Dispersion
The phenomenon in which the non-aqueous substance forms fine particles in water and is
uniformly dispersed is called dispersion. The dispersion system of the cosmetic includes powders,
solvents and dispersing agents. Powders can be divided into inorganic pigments (such as talc,
mica, titanium dioxide and carbon black) and organic pigments. Their function is mainly to make
cosmetics have good color and good sunscreen effect. Solvents are classified into water and
non-water. The dispersing agent as a medium has two types of hydrophilicity and lipophilicity.
And the dispersing agents are mainly classified into hydrophilic dispersing agents and lipophilic
dispersing agents. Many surfactants used in dispersants are both emulsifiers and dispersants. In
order to sufficiently disperse the powder in the liquid, it is necessary to make the liquid wet the
surface of the powder well, so the HLB of the powder surface and the dispersion medium should
first be considered when selecting the surfactant.
Cleaning
Cleaning products mainly include shampoo, shower gel and facial cleanser. In addition to their
cleansing, foaming and wetting functions, these products must also be mild to the skin. Therefore,
the surfactant used for cleaning must not damage the epidermal cells, does not penetrate into
the skin, and keeps the skin in a normal state. Anionic surfactants have been used for cleaning for
a long time. The detergency of soap is unmatched by other detergents. Sodium lauryl sulfate is a
commonly used raw material in the cleaning cosmetics, which can achieve a good cleaning effect
on the skin. Amphoteric surfactants such as imidazoline, cocamidopropyl betaine and amino
acids are mild cleansing surfactants and are an indispensable component in the formulation of
facial cleansers, shampoos and baby shampoos.
Softening
Cationic surfactants have good softening and antistatic properties and are therefore the main
conditioning agents in hair care products such as hair conditioners. The most commonly used

2. cationic surfactants are the monoalkyl and dialkyl quaternary ammonium salts such as the
C16-18 monoalkylamine salt, the double C16-18 alkyl quaternary ammonium salt and the
alkylbenzyl quaternary ammonium salt.
Wetting and penetration
Cosmetics must not only have cosmetic effects, but also give people a comfortable and soft
feeling when used, and these effects are inseparable from the moisturizing effect of surfactants.
As a main component of biological cells, phospholipids play an important role in the metabolism
of cell and permeability mediation of cell membrane, and have good moisturizing and
penetration effect to the skin. The sophorolipid biosurfactant has a peculiar affinity for the skin,
which makes the skin feel soft and moist. Biochemical active substances, vitamin derivatives,
enzyme preparations, cell growth factors (EGF, DFGF), collagen, elastin, ceramide and hyaluronic
acid can be prepared by biochemical synthesis and they can be used in cosmetics. These
substances can penetrate into the skin, participate in the metabolism of skin cells, change the
structure of the skin to achieve anti-wrinkle, anti-aging and whitening effects.