What Are Surfactants?
Surfactants (short for surface-active agents) are chemical compounds that dramatically reduce the surface tension of liquids and enable the mixing of mutually immiscible substances — typically water and fats.
Without surfactants, your shampoo, detergent, industrial cleaner, or agricultural spray would not work. Global surfactant production exceeds 17 million tons per year, with Europe consuming approximately 4 million tons.
Key Definition
A surfactant is an amphiphilic molecule — it has a hydrophilic head (loves water) and a hydrophobic tail (loves fats). This allows it to sit at the interface of water and oil and reduce surface tension.
How Do Surfactants Work?
A surfactant molecule orients itself at the interface of two phases — water and air, or water and oil. The hydrophilic part points toward water, the hydrophobic part toward oil or air.
Micelle Formation
Above a certain concentration (the so-called CMC — critical micelle concentration), surfactant molecules begin to form micelles — spherical structures with a hydrophobic core and a hydrophilic surface. The micelle core solubilizes (dissolves) grease and dirt, which is then washed away with water. This is how cleaning works.
Reduction of Surface Tension
Pure water has a surface tension of approximately 72 mN/m. Adding a surfactant can reduce it to 25–35 mN/m — water then wets surfaces better, penetrating fabrics and soil texture (in agriculture) or material pores.
Emulsification
Surfactants stabilize emulsions — dispersions of oil droplets in water (O/W) or water in oil (W/O). This function is key in cosmetics (creams, lotions), food (mayonnaise), and industry (cutting fluids).
Types of Surfactants
Surfactants are divided into four basic groups based on the electrical charge of the hydrophilic part. Each group has different properties and application areas.
Anionic Surfactants — Negative Charge
The most widespread group. Excellent cleaning power and foaming. Sensitive to water hardness and incompatible with cationic surfactants.
SLS (Sodium Lauryl Sulfate)
toothpastes, technical cleaning
SLES (Sodium Laureth Sulfate)
shampoos, shower gels, detergents
LAS (Lineární Alkylbenzensulfonát)
laundry and cleaning products
LABSA (Kyselina alkylbenzensulfonová)
industrial base for LAS
AOS (Alpha-Olefin Sulfonát)
gentle cleaning, compatible with hard water
Mýdla (sodná/draselná sůl MK)
natural cleaning, creams, shampoos
Nonionic Surfactants — No Charge
Compatible with virtually everything. Resistant to hard water, gentle on skin. Lower foaming, higher price than anionic.
APG (Alkyl Polyglukosidy)
cosmetics, eco-friendly cleaning, agriculture
Ethoxylované alkoholy (C12-14 EO7)
industrial cleaning, textiles
Polysorbáty (Tween 20, 60, 80)
solubilization, cosmetics, pharmaceuticals
EO/PO blokové kopolymery (Pluronic)
industrial cleaning, low-foam applications
Kokamid DEA/MEA
thickening, foam booster
PEG-40 hydrogenated castor oil
solubilizer for essential oils
Cationic Surfactants — Positive Charge
Strong affinity for negatively charged surfaces (hair, textiles, bacterial membranes). Key for disinfection, fabric softeners, and conditioners. Incompatible with anionic surfactants.
Benzalkonium Chloride (BAC/BTAC)
disinfection, preservation, eye preparations
Cetrimonium Chloride (CDAC)
hair conditioners, antistatics
Ester Quaty (DEEDMAC)
fabric softeners, biodegradable
DDAC (Didecyl dimethyl ammonium Cl)
industrial disinfection
Amphoteric Surfactants — Charge Depends on pH
Positive charge at low pH, negative at high pH. Compatible with both anionic and cationic surfactants. Mild, gentle on skin. Ideal for baby cosmetics and combinations.
CAPB (Cocamidopropyl Betaine)
shampoos, shower gels, baby cosmetics
Aminoxidy (Lauramine Oxide)
thickening, foam stabilizer
Sultainy (CAPSO)
very gentle, sensitive skin
Imidazolinové betainy
industrial cleaning, harsh conditions
HLB Value — The Key to Choosing an Emulsifier
HLB (Hydrophilic-Lipophilic Balance) is a number on a scale of 0–20 that expresses the balance between the hydrophilic and lipophilic parts of a surfactant molecule. It was developed by William Griffin in 1949 and remains the most widely used tool for selecting an emulsifier.
| HLB Range | Function | Examples |
|---|---|---|
| 1–3 | Defoamers | Span 85, silikonové odpěňovače |
| 4–6 | W/O Emulsifiers | Span 80 (HLB 4,3), Arlacel 83 |
| 7–9 | Wetting Agents | Span 20, Brij 35 (nízký) |
| 8–16 | O/W Emulsifiers | Tween 20 (HLB 16,7), Emulgade SE |
| 13–15 | Detergents | SLES, APG, LAS |
| 15–18 | Solubilizers | Tween 80 (HLB 15), PEG-40 HCO |
How to Use HLB in Practice?
Every oil has a required HLB. For example, mineral oil requires HLB 10–12, IPM (isopropyl myristate) HLB 12–14, soybean oil HLB 6–8. Choose an emulsifier (or combination) with an HLB matching your oil.
Practical Tip: Combine Two Emulsifiers
HLB is additive. Combining Span 80 (HLB 4.3) + Tween 80 (HLB 15) in a 20:80 ratio gives a resulting HLB = 0.2×4.3 + 0.8×15 = 12.9. Such a combination forms a more stable emulsion than a single emulsifier with the same HLB.
CMC — Critical Micelle Concentration
CMC (Critical Micelle Concentration) is the surfactant concentration at which micelles begin to form. Below the CMC, surfactant molecules are dispersed as monomers — the surfactant reduces surface tension but does not form micelles and does not clean.
| Surfactant | CMC (mM) | CMC (%) |
|---|---|---|
| SDS / SLS | 8,1 | 0,23 |
| SLES 2EO | 0,5–1 | 0,015–0,03 |
| CAPB (Cocamidopropyl Betaine) | 1–4 | 0,03–0,12 |
| APG C8/C10 | 2–5 | 0,07–0,18 |
| Tween 80 (Polysorbát 80) | 0,012 | 0,001 |
| LAS | 1–3 | 0,03–0,09 |
Effective cleaning requires a concentration of 5–100× the CMC. In practice, this means that for SLES (CMC ≈ 0.02%) you need at least 0.1–2% in the product for a cleaning effect — typical shampoos contain 8–15% SLES, i.e., 400–750× the CMC.
Surfactants in Industrial Applications
Cosmetics & Personal Care
- →Shampoos and shower gels: SLES 12–15% + CAPB 3–5% + cocamide DEA 2%
- →Conditioners: cetrimonium chloride 0.5–3% (cationic)
- →Creams and lotions: Emulgade SE, Olivem 1000, Tego Care PBS 6
- →Baby cosmetics: APG + amphoacetate — low irritation
Industrial Cleaning
- →Alkaline industrial cleaners: LAS + nonionic surfactant + NaOH
- →CIP (Clean-in-Place) food industry: low-foam EO/PO surfactants
- →Metal degreasing: ethoxylated alcohols C12-18 EO7
- →Industrial washing machines: block copolymers Pluronic L61, L64
Agriculture
- →Wetting agents for pesticides: APG, ethoxylated alcohols — improve leaf coverage
- →Emulsifiers for EC formulations: Soprophor BSU, Arkopal N-100
- →Penetrants: alkyl polyglucosides increase active ingredient uptake
- →Adjuvants: reduce the contact angle of a drop on the leaf below 30°
Coatings & Paints
- →Pigment dispersants: Disperbyk-190, Tego Dispers 740W
- →Substrate wetting agents: BYK-346, Tego Wet 240 — reduce contact angle
- →Defoamers: Tego Foamex 800 (silicone), Surfynol 104
- →Coalescing agents: Texanol, DPnB — aid film formation
Overview of Key Surfactants
SLES (Sodium Laureth Sulfate)
AnionicHLB
~40 (vel. HMW)
CMC
0,5–1 mM
pH Stability
6–8
Shampoos, shower gels, detergents. Gentler than SLS due to ethoxylation.
View products in the catalog →LAS / LABSA
AnionicHLB
—
CMC
1–3 mM
pH Stability
7–10
Laundry and cleaning products. LABSA is the acid form neutralized with NaOH to LAS.
View products in the catalog →APG C8/C10/C12 (Alkyl Polyglukoside)
NonionicHLB
12–14
CMC
2–5 mM
pH Stability
3–11
Bio-surfactant from renewable sources. Cosmetics, eco-friendly cleaning products.
View products in the catalog →CAPB (Cocamidopropyl Betaine)
AmphotericHLB
—
CMC
1–4 mM
pH Stability
4–9
Shampoos, baby cosmetics. Synergistically increases foaming and viscosity of SLES.
View products in the catalog →Benzalkonium Chloride (BAC)
CationicHLB
—
CMC
0,1–0,5 mM
pH Stability
5–9
Disinfection, preservation. MIC for Gram+ bacteria: 10–50 ppm.
View products in the catalog →Polysorbát 80 (Tween 80)
NonionicHLB
15
CMC
0,012 mM
pH Stability
4–8
Solubilizer for essential oils and vitamins. Cosmetics, pharmaceuticals, food industry.
View products in the catalog →Browse the entire category: Surfactants · Surface-Active Agents
Legislation & REACH
Surfactants are subject to extensive legislation in the EU. Key regulations that every buyer and formulator must know:
REACH (ES 1907/2006)
Registration, evaluation, and authorization of chemicals. All surfactants above 1 t/year must be registered. As a buyer, you are a downstream user and have the right to an up-to-date SDS.
CLP (ES 1272/2008)
Classification and labeling. Surfactants are typically classified as Aquatic Chronic 3 (harmful to aquatic life). Ensure correct product labeling.
Nařízení o detergenty (ES 648/2004)
Surfactants in laundry and cleaning products must be biodegradable (OECD 301 test > 60% mineralization). APEO and NPEO are banned.
Kosmetické nařízení (ES 1223/2009)
Surfactants in cosmetics must meet the requirements of Annex II (banned substances) and III (restricted substances). Monitor cocamide DEA for SVHC status.
Biocidní nařízení BPR (EU 528/2012)
Cationic surfactants (BAC, DDAC) used as disinfectants must be approved under BPR. Verify the status of the specific product.
Banned in the EU
APEO (Alkylphenol ethoxylates) — nonylphenol ethoxylates (NPE), octylphenol ethoxylates — are banned in cleaning products and restricted in other applications. Replace them with APG or linear ethoxylated alcohols.
How to Choose the Right Surfactant for Your Formulation
1. Define the Application
Cosmetics, industrial cleaning, agriculture, coatings? Each area has different requirements for performance, pH, foaming, and legislation.
2. Determine the Required Properties
Foaming? Cleaning power? Skin gentleness? Hard water resistance? Biodegradability? Low CMC?
3. Choose the Type of Surfactant
Anionic for performance and foam. Nonionic for hard water and gentleness. Cationic for disinfection or conditioning. Amphoteric for combinations.
4. Verify HLB for Emulsification
If you are formulating an emulsion, determine the required HLB of your oil and choose an emulsifier or combination.
5. Check pH Compatibility
SLES stable at pH 5–8. APG stable at pH 3–11. Soaps degrade below pH 8.
6. Perform Screening and Formulation
Prepare 3–5 samples with different surfactants or combinations. Test CMC, foaming, viscosity, stability.
7. Verify Legislation
Check REACH registration, SDS, SVHC status, and specific restrictions for your application.
Frequently Asked Questions
What is a surfactant?+
What is the difference between anionic and nonionic surfactants?+
What is the HLB value?+
What is the CMC of a surfactant?+
How do I choose the right surfactant for my formulation?+
Are surfactants safe for the environment?+
Looking for a Specific Surfactant?
GCG Group supplies more than 300 surfactants — anionic, nonionic, cationic, and amphoteric. Samples on request, technical support, individual pricing.