Non-ionic surfactants: characteristics, functions and cosmetic applications
Non-ionic surfactants are characterized by the absence of electrical charge in their hydrophilic portion. This property allows them to act with excellent skin tolerance, compatibility with other ingredients, and high functional versatility.Their hydrophilic group typically contains strong polar bonds, such as –OH (alcohol) or –O– (ether). There are several ways to obtain this hydrophilic structure, including:
- From ethylene oxide
- From sugars (glucose, fructose...)
- From glycerin
- Primary surfactants
- Co-surfactants
- Thickeners
- Solubilizers
- Re-fatting agents
What is a surfactant and how are they classified?
A surfactant is an amphiphilic molecule, with one part soluble in water (hydrophilic) and another soluble in oils (lipophilic), allowing it to reduce water surface tension and help form emulsions.Depending on their charge, surfactants are classified into:
| Type | Charge | Characteristics |
| Anionic | Negative | Good detergency and foam, more irritating |
| Cationic | Positive | High affinity with keratin, conditioners |
| Amphoteric | Variable | Mildness and compatibility |
| Non-ionic | None | Stable, mild and versatile |
Chemical characteristics of non-ionic surfactants
Their hydrophilic group usually contains polar bonds such as –OH (alcohol) or –O– (eter). The hydrophilic fraction can be obtained from:- Ethylene oxide (EO)
- Sugars (e.g., glucose, fructose)
- Glycerin
Key functions of non-ionic surfactants in cosmetics
Co-surfactants
They are combined with other surfactants (e.g. anionic) to form mixed micelles, which improve:- Foam quality (volume, texture, stability)
- Viscosity of the formulation
- Reduction of irritation
Thickeners
Some non-ionic surfactants modify the micelles of primary surfactants, increasing their size and reducing mobility, which results in higher viscosity.This enables:
- Reduced use of salt to thicken (less irritant potential)
- Richer, more stable textures
Solubilizers
When the hydrophilic fraction represents a large portion of the molecule’s weight, the surfactant can solubilize lipophilic substances (e.g. oils, perfumes, liposoluble vitamins) in aqueous media.In other words, it helps dissolve oily ingredients in water. Result: clear, stable systems -- ideal for micellar waters, toners or serums.
Solubilizing capacity can be estimated with the HLB (Hydrophilic-Lipophilic Balance):
| HLB | Application |
| 4 - 6 | W/O emulsifier |
| 7 - 15 | Humectants |
| 8 - 18 | O/W emulsifier |
| 10 - 15 | Detergent |
| 10 - 18 | Solubilizer |
The higher the HLB, the greater the water solubility.
Re-fatting agents
Certain non-ionic esters can deposit on the skin or hair during rinsing, providing a soft and emollient feel. They help restore lipids lost during cleansing, leaving a nourished, smooth sensation.Commonly used in:
- Shower gels and mild shampoos
- Baby care products
- Formulas for sensitive or dry skin
Why choose non-ionic surfactants?
Technical advantatges- No electrical charge
- Skin mildness
- High chemical stability
- Structural versatility
- Natural and biodegradable origin
- Universal compatibility
- Ideal for sensitive skin
- Works in a broad pH range
- Multiple uses in one formula
- Aligns with sustainability trends
Conclusion
Non-ionic surfactants stand out not only for their mildness and compatibility, but also for their functional versatility. They can act as foaming agents, co-surfactants, solubilizers, thickeners or re-fatting agents, adapting to a wide variety of formulation needs.If your goal is to design mild, efficient, and well-tolerated cosmetic products, whether certified natural or not, non-ionic surfactants are an essential technical resource.