Non-Ionic Surfactants in Focus: Alcohol Ethoxylates, Polyethylene Glycol Trimethylnonyl Ether, and Triton™ X-100
Non-Ionic Surfactants in Focus: Alcohol Ethoxylates, Polyethylene Glycol Trimethylnonyl Ether, and Triton™ X-100
Introduction
Non-ionic surfactants are a broad class of amphiphilic molecules that contain both hydrophobic (oil-loving) and hydrophilic (water-loving) segments, but crucially lack ionic charges. Their hydrophilicity arises from poly(ethylene oxide) (EO) chains that hydrogen bond with water, while their hydrophobic portions vary — linear or branched alkyls, or alkylphenyl groups. This structural motif makes them versatile: they can reduce surface tension, form micelles, stabilize emulsions, solubilize hydrophobic compounds, and interact gently with biomolecules.
Among non-ionic surfactants, three representatives are especially notable for their scientific and industrial importance:
TERGITOL™ 15-S-9 (Secondary Alcohol Ethoxylate)
· Chemical identity: A mixture of C11–C15 secondary alcohols reacted with ethylene oxide to an average of 9 EO units (often listed under CAS 68131-40-8 or 84133-50-6).
· Key feature: Represents the secondary alcohol ethoxylates (SAEs) family.
· Why important: Serves as a benchmark industrial surfactant — widely applied in detergents, coatings, agrochemicals, textiles, pulp & paper, and increasingly in labs as an alternative to older surfactants like Triton™ X-100.
· Environmental note: Readily biodegradable (OECD 301E) and positioned as a safer, sustainable replacement for alkylphenol ethoxylates (APEs).
Polyethylene Glycol Trimethylnonyl Ether (TMN-9 and related grades)
· Chemical identity: An ethoxylated branched C₁₂ alcohol, specifically a trimethylnonyl hydrophobe attached to a poly(ethylene oxide) chain (commonly 9–10 EO units, CAS 60828-78-6).
· Key feature: Belongs to the TMN family of branched non-ionic surfactants.
· Why important: Often marketed as a direct, APE-free alternative to Triton™ X-100 in biochemistry and protein science — maintaining solubilization and non-denaturing properties, while avoiding environmental issues associated with APEs.
· Flexibility: Available in multiple EO chain lengths (e.g., TMN-6, TMN-9, TMN-10), which allow tuning of solubility and cloud point for different applications.
Triton™ X-100 (Octylphenol Ethoxylate)
· Chemical identity: An alkylphenol ethoxylate (APE), specifically p-(1,1,3,3-tetramethylbutyl)phenol with an average of ~9–10 EO units (CAS 9002-93-1).
· Key feature: Long the standard non-ionic detergent in life science laboratories.
· Why important: Extensively documented for membrane protein solubilization, gentle cell lysis, and use in countless biochemical protocols, Triton™ X-100 remains a reference point for lab detergents.
· Limitation: Breaks down into octylphenol, which is persistent and an endocrine disruptor. As a result, it is restricted under EU REACH (Annex XIV). Alternatives such as 15-S-9 and TMN-9/10 are increasingly used.
Alcohol Ethoxylates (AEs) carried by Aladdin
Aladdin catalog | CAS mumber | Product name | Grade & Purity |
Secondary alcohol ethoxylates (SAEs). |
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|
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84133-50-6 | Polyethylene glycol trimethylnonyl ether | Type 15-S-7 | |
84133-50-6 | Polyethylene glycol trimethylnonyl ether |
| |
84133-50-6 | TERGITOL™ 15-S-5 | Non-ionic surfactant | |
84133-50-6 | TERGITOL™ 15-S-40 | 70% aqueous solution | |
84133-50-6 | TERGITOL™ 15-S-15 | Non-ionic surfactant | |
84133-50-6 | TERGITOL™ 15-S-9 | nonionic | |
TMN family |
|
|
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60828-78-6 | Tergitol® TMN 10 | ≥90% active ingredients basis | |
60828-78-6 | Tergitol® TMN 6 | ≥90% active ingredients basis | |
60828-78-6 | Tergitol® TMN 3 | ≥90% active ingredients basis | |
Triton™-type |
|
|
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9002-93-1 | Triton™ X-100 | Suitable for molecular biology | |
9002-93-1 | Triton™ X-45 | Cloud Point 39.4 - 44.8 °C | |
9002-93-1 | Triton™ X-100 | Ultra pure | |
9002-93-1 | Triton™ X-100 | Biochemical | |
9002-93-1 | Triton™ X-100 | suitable for electrophoresis | |
9002-93-1 | TRITON™X-305 Surfactant | 70% in H2O |
Core Property Parameters and Their Impact on Applications
Comparative Core Properties
Property (25 °C unless noted) | TERGITOL™ 15-S-9 (SAE) | TMN-9 / TMN-10 (PEG trimethylnonyl ether) | Triton™X-100 (Octylphenol Ethoxylate) |
Representative CAS | 68131-40-8 (C11–C15 SAE)； | 60828-78-6 | 9002-93-1 |
Hydrophobe | Linear/branched secondary C11–C15 alkyl | Branched C12 (trimethylnonyl) | Aromatic ring with branched C8 substituent |
Ethoxylation (EO units) | ~9 (distribution) | ~9–10 (distribution) | ~9–10 (distribution) |
HLB (hydrophile–lipophile balance) | 13.3 | ~13 (depends on grade; TMN-6, TMN-10 vary) | ~13.5 |
Cloud Point (1 % aq.) | 60 °C | 36 °C (TMN-6) → 76 °C (TMN-10) | 63–69 °C |
CMC (Critical Micelle Concentration) | 52 ppm (≈0.087 mM) | Supplier dependent; ~0.1–0.3 mM (varies by EO) | 0.22–0.24 mM |
Surface Tension (1 %) | ~30 mN·m⁻¹ | Similar range (non-ionic AE class) | ~33 mN·m⁻¹ |
Biodegradability | Readily biodegradable (OECD 301E); APE-free | Marketed as APE-free, readily biodegradable | APE, degrades to octylphenol (persistent, endocrine-disrupting) |
Regulatory Status | No restrictions | No restrictions | Restricted under EU REACH (Annex XIV) |
Here is a figure showing the three molecules with different hydrophobes highlighted
How These Properties Drive Applications
Hydrophile–Lipophile Balance (HLB)
All three surfactants sit around HLB 13–14, the detergency / O/W emulsifier zone.
Practical meaning:
• Good at solubilizing oils in water,
• Strong detergency/wetting,
• Useful in cleaning, agro adjuvants, coatings, biochemistry.
Cloud Point
• Indicates the temperature above which the surfactant loses water solubility.
• 15-S-9 (~60 °C): stable in room-temperature formulations, but aqueous products can haze above 60 °C.
• TMN grades (36–76 °C): tunable → TMN-6 suited for low-temp wetting, TMN-10 for high-temp processes.
• Triton™ X-100 (~63–69 °C): historically convenient for lab protocols that operate at room temp to 37 °C.
Critical Micelle Concentration (CMC)
• 15-S-9: very low CMC (52 ppm ≈ 0.087 mM) → works efficiently at ppm-level dosing, excellent for rinseability (e.g., HI&I cleaning).
• Triton™ X-100: higher CMC (~0.22–0.24 mM), but still effective at modest concentrations.
• TMN-9/10: CMC values are similar in range (order of 0.1–0.3 mM); depend on EO chain length.
• Practical meaning: Lower CMC = more efficient micelle formation, so less surfactant is needed to solubilize oils or proteins.
Surface Tension
• All reduce surface tension to ~30–33 mN·m⁻¹ at typical concentrations → strong wetting and spreading.
• Applications: essential for detergency (hard-surface cleaning, textile wetting, coating dispersions).
Biodegradability and Regulation
• 15-S-9 and TMN-x: readily biodegradable, APE-free → safe for modern consumer/industrial products.
• Triton™ X-100: produces octylphenol upon degradation → persistent, endocrine-disrupting, restricted under EU REACH (Annex XIV, sunset Jan 2021).
Typical Application Areas of 15-S-9, TMN-9, and Triton™ X-100
Surfactant | Industrial / Commercial Uses | Biochemistry / Life Science Uses |
TERGITOL™ 15-S-9 (Secondary Alcohol Ethoxylate) | • Home & Industrial Cleaning (HI&I): detergents, degreasers, hard-surface cleaners, laundry aids | • Increasingly used as an APE-free replacement for Triton™ X-100 in buffers and lysis solutions (protein solubilization, non-denaturing detergency) |
Polyethylene Glycol Trimethylnonyl Ether (TMN-9 / TMN-10) | • HI&I Cleaners: surface cleaners, degreasers, detergent blends | • Biochemistry: widely used as an APE-free substitute for Triton™ X-100, especially TMN-9 and TMN-10 |
Triton™ X-100 (Octylphenol Ethoxylate) | • Historically used in detergents, emulsifiers, and cleaners — but now largely phased out industrially due to REACH restrictions | • Classic laboratory detergent: |
References
1. Dow Chemical Company. TERGITOL™ 15-S-9 Surfactant, Technical Data Sheet. Form No. 119-01950-1107, The Dow Chemical Company, Midland, MI.
2. European Chemicals Agency (ECHA). Substance Information: Alcohols, C11–15, secondary, ethoxylated. EC No. 614-295-4; CAS No. 68131-40-8. Available at: https://echa.europa.eu/substance-information.
3. European Chemicals Agency (ECHA). Substance Information: Alcohols, C12–C14, secondary, ethoxylated. CAS No. 84133-50-6. Available at: https://echa.europa.eu/substance-information.
4. Merck KGaA (Sigma-Aldrich). Triton™ X-100, Laboratory Grade, Product Information Sheet (T8532). Darmstadt, Germany.
5. Merck KGaA (Sigma-Aldrich). TERGITOL™ TMN-6 Product Listing. Product page.
6. Merck KGaA (Sigma-Aldrich). TERGITOL™ TMN-10 Product Listing. Product page.
7. Merck KGaA (Sigma-Aldrich). TERGITOL™ TMN-9 / TMN-10 Application Notes. Product pages.
8. Neofroxx GmbH. TERGITOL™ 15-S-9 Technical Note. Neofroxx Specialty Reagents, Germany.
9. European Chemicals Agency (ECHA). Authorisation List (Annex XIV of REACH). Entry for nonylphenol ethoxylates (NPEs) and octylphenol ethoxylates (OPEs). Sunset date: 4 January 2021. Available at: https://echa.europa.eu/authorisation-list
Aladdin: https://www.aladdinsci.com/