Anionic surfactants

Characteristics and properties of anionic surfactants

Surfactants are among the most versatile chemical compounds in industry. They are amphiphilic molecules with both hydrophilic and hydrophobic parts in their structure. This unique structure gives them exceptional surface properties.

Amphiphiles with a negative charge on their polar group are called anionic surfactants. In solutions and mixtures, they are located at the interface between phases of different polarity. This allows them to effectively reduce surface and interfacial tension.

Key properties of anionic surfactants:

• Emulsifying ability,
• Excellent wetting properties,
• High and stable foaming ability (over a wide pH range),
• Very good washing and cleaning properties,
• Hydrotropic effect,
• Good biodegradability.

Key areas where anionic surfactants are used

Cosmetics and personal care products

Anionic surfactants are the leading cleaning ingredients in cosmetic products. They are found in products such as hair shampoos, shower gels, liquid soaps, hair conditioners, hairsprays, etc. Some compounds in this group are exceptionally mild on the skin, which makes them suitable for use in children’s cosmetics and selected intimate hygiene products.

Detergents and household chemicals

Due to their excellent cleaning properties, anionic surfactants are used as the main active ingredients in soaps and chemical detergents, as well as other cleaning and washing formulations. Most of them are highly resistant to hard water, which makes them ideal for use in dishwashing liquids. In addition, they produce large amounts of foam when mixed. Some anionic surfactants are hypoallergenic, which is why they are often used in detergents designed for sensitive skin. In addition to household chemicals, anionic surfactants are often used in the automotive industry, where they are ingredients in car cleaning and care products.

Production of paints and varnishes

Anionic surfactants are particularly important components in formulations created during the mixing of paints and varnishes. The surface action of these compounds ensures the stability of the pigment in the mixture and its good dispersion. Importantly, they are compatible with most components commonly used in the production of paints and varnishes (inorganic pigments and mineral fillers, dispersing and wetting agents, rheology modifiers and anti-foaming agents).

Agrochemical industry

In agrochemical formulations, anionic surfactants act as dispersing agents and emulsifiers. They stabilise the resulting mixtures and prevent their delamination. They work well with all types of emulsions, concentrates and dispersions used in the agrochemical industry. However, they show the best application performance with suspension concentrates.

Construction

Some anionic surfactants act as air-entraining agents added to construction mixtures. They are used, for example, in the production of drywall, enabling the manufacture of lightweight and durable materials.

Other industrial applications

• Emulsion polymerisation – they stabilise the dispersion. This allows control over particle size in various systems.
• Fire extinguishing agents – they are components of synthetic fire extinguishing agents, where they act as basic foaming agents.
• Textile industry – they play a key role in processes such as wetting, washing and dyeing fabrics.
• Metallurgical industry – they are included in metalworking preparations. Used for cleaning hard surfaces, as well as in metal cutting, grinding and stamping processes.
• Food and food industry – some anionic surfactants have been approved for use as indirect food additives.