Tween 20 and Tween 80 as Non-Ionic Surfactants: Structure, Properties, and Applications

Introduction

Non-ionic surfactants are indispensable tools in modern science, pharmaceuticals, food technology, and cosmetics, where they function as emulsifiers, stabilizers, and solubilizers. Among them, Tween 20 (Polysorbate 20, CAS 9005-64-5) and Tween 80 (Polysorbate 80, CAS 9005-65-6) are two of the most widely used members of the polysorbate family. Both are derived from sorbitan, a dehydrated form of sorbitol, esterified with fatty acids and further modified with approximately 20 units of polyoxyethylene. This structural architecture provides them with an amphiphilic nature—simultaneously hydrophilic and lipophilic—which underpins their ability to reduce surface tension, stabilize emulsions, and protect sensitive molecules.

• Tween 20 = polyoxyethylene (20) sorbitan monolaurate (major fatty acid: lauric, ≥ 40% lauric).

• Tween 80 = polyoxyethylene (20) sorbitan monooleate (major fatty acid: oleic, ≥ 58% oleic).

• EO content: average ~20 EO units distributed over ~4 polyoxyethylene arms on a sorbitan/isosorbide backbone.

Commercial polysorbates are mixtures (mono-, di-, tri-, tetra-esters; sorbitan vs. isosorbide cores; a distribution of EO chain lengths).

“Tween” is a historic trade name introduced by Atlas Powder Company in the 1940s (now within Croda’s portfolio). HLB (hydrophile–lipophile balance), the system widely used to select surfactants, was developed in this lineage.

Quick Comparison of Tween 20 vs. Tween 80

Feature	Tween 20 (Polysorbate 20)	Tween 80 (Polysorbate 80)
CAS No.	9005-64-5	9005-65-6
Chemical name	Polyoxyethylene (20) sorbitan monolaurate	Polyoxyethylene (20) sorbitan monooleate
Fatty acid tail	Lauric acid (C12:0, saturated)	Oleic acid (C18:1, unsaturated)
Backbone	Sorbitan (dehydrated sorbitol)	Sorbitan (dehydrated sorbitol)
Hydrophilic chains	~20 ethylene oxide (EO) units	~20 ethylene oxide (EO) units
HLB value	~16.7 (more hydrophilic)	~15.0 (slightly less hydrophilic)
Key property	Better at wetting, blocking nonspecific binding	Stronger solubilizer, micelle formation at lower concentration
Stability note	More resistant to oxidation	More prone to oxidation (due to unsaturated oleate)

This figure help for better understand the two structures.

Tween 20 vs. Tween 80 provided by Aladdin

Aladdin catalog	Product name	Grade & Purity
T476411	TWEEN® 20	non-ionic, aqueous solution, 10% (w/v)
P434501	Polyoxyethylene (20) sorbitan monolaurate solution	Polyoxyethylene (20) sorbitan laurate solution, ~10% in H2O
T434505	TWEEN® 20	Suitable for molecular biology, viscous liquids
T104863	TWEEN® 20	viscous liquid
T434506	TWEEN® 20	for cell culture, viscous liquid
T118633	TWEEN® 80	for cell culture
T434509	TWEEN® 80 solution	10%, low peroxide
T434510	TWEEN® 80	from non-animal source
T485985	TWEEN® 80	viscous liquid, Preservative Free, Low-peroxide; Low-carbonyls
T104866	TWEEN® 80	pharmaceutical grade
T104865	TWEEN® 80	viscous liquid

Key physicochemical properties of Tween 20 vs. Tween 80

Property	Tween 20 (PS20)	Tween 80 (PS80)	Why it matters
HLB	16.7	≈ 15.0	Higher HLB favors O/W emulsions, wetting, and protein adsorption control; lower HLB leans slightly more lipophilic/solubilizing.
CMC (25 °C)	≈ 0.06 mM (≈ 60 µM)	≈ 0.012 mM (≈ 12 µM)	Lower CMC (PS80) forms micelles at lower doses → stronger solubilization of hydrophobes but can interact more with membranes.
Cloud point	~ 76 °C	~ 65 °C	Above cloud point, solutions turn turbid; relevant for heat-steps/sterilization.
Viscosity (25 °C)	Viscous liquid	~ 300–620 mPa·s	Handling/pipetting; mixing energy.
Density (25 °C)	~1.095–1.10 g mL⁻¹	~1.064–1.10 g mL⁻¹	Mass → volume conversions.

How these properties steer practical use

• HLB 16.7 vs 15.0:

PS20 is the “more hydrophilic” choice for O/W emulsions, wetting, and minimizing nonspecific protein adsorption (e.g., WB/ELISA buffers). PS80, being slightly less hydrophilic and more hydrophobic (C18:1), solubilizes lipophilic APIs/excipients more efficiently and often gives stronger interfacial protection at lower dose.

• CMC:

PS80 reaches micellization at lower concentration, so 0.001–0.02% can already be functional; PS20 often used 0.005–0.05% for biologics and 0.05% in immunoassay washes. (Ranges from peer-reviewed formulation literature.)

• Cloud point:

Avoid prolonged heating near/above cloud point; autoclaving polysorbates is generally discouraged (color change, degradation; catalyzed by trace metals).

Applications and Limitations of Tween 20 and Tween 80

Application Area	Tween 20 (Polysorbate 20)	Tween 80 (Polysorbate 80)	Limitations / Precautions
Biologics & Pharma	• Stabilizes proteins in monoclonal antibody and enzyme formulations.  • Prevents interfacial adsorption/aggregation during agitation, freeze–thaw, or device contact. • Typical use: 0.001–0.01% w/v.	• Enhances solubility of poorly soluble APIs (lipophilic drugs, vitamins). • Used as excipient in vaccines and parenterals (0.001–0.02% w/v). • Provides strong interfacial protection due to lower CMC.	• Both undergo oxidation/hydrolysis → form peroxides and free fatty acids (FFAs) that destabilize proteins.  • Tween 80 more oxidation-prone (oleic unsaturation).  • Lot-to-lot variability due to heterogeneity.
Diagnostics & Life Sciences	• Standard in ELISA, Western blot, IHC buffers (~0.05% w/v) to reduce nonspecific binding.  • Used in cell lysis/permeabilization buffers at 0.01–0.5%.	• Occasionally in cell culture media to solubilize hydrophobic nutrients.  • Can disrupt membranes at higher concentrations.	• Excess Tween 20 → strips membrane proteins and reduces assay signals.  • Tween 80 can be cytotoxic and alter lipid membranes.
Food Industry (E-numbers)	• Approved emulsifier E432.  • Stabilizes beverages, sauces, bakery fillings.  • Creates fine O/W emulsions, prevents phase separation.	• Approved emulsifier E433.  • Stabilizer in ice cream, whipped toppings, margarine; improves fat–air incorporation, smooth texture.	• Both restricted by maximum permitted levels (EU, FDA).  • High intake → gastrointestinal discomfort.  • Oxidation can lead to off-flavors in food matrices.
Cosmetics & Personal Care	• Found in facial cleansers, serums, lotions.  • Mild surfactant, improves wetting and spreadability, light texture.	• Present in shampoos, creams, oil-rich lotions.  • Strong emulsification of vegetable oils and fragrances.	• Both can undergo oxidative rancidity → yellowing, odor development.  • Require antioxidants (e.g., tocopherols) and light-protection packaging.
Industrial & Other Uses	• Mild detergent for glassware and laboratory cleaning.  • Used in pesticide formulations as a gentle emulsifier.	• Dispersant/solubilizer in paints, coatings, textiles.  • Used in certain microbial culture media (to improve dispersion of hydrophobic substrates).	• Thermal instability (cloud point ~65–76 °C). • Avoid autoclaving; prefer sterile filtration.  • Storage: protect from light, oxygen, metals.

References:

1. European Commission. Regulation (EU) No 231/2012: Specifications for food additives including Polysorbates E432–E433.

2. European Commission. Regulation (EC) No 1333/2008: On food additives.

3. United States Pharmacopeia (USP–NF). Polysorbate 20 and Polysorbate 80 monographs.

4. European Pharmacopoeia (Ph. Eur.) and Japanese Pharmacopoeia (JP) entries for Polysorbates.

5. BASF. Kolliphor® PS 20 and Kolliphor® PS 80: Technical Information. BASF Pharma Solutions.

6. Croda International. Tween™ 20 and Tween™ 80 product datasheets.

7. Merck / Sigma-Aldrich. Polysorbate 20 (CAS 9005-64-5) and Polysorbate 80 (CAS 9005-65-6): Product Specifications.

8. Singh, S.K., et al. (2012). “Polysorbate degradation and particle formation in protein formulations.” Journal of Pharmaceutical Sciences, 101(10), 3526–3535.

9. Ha, E., Wang, W., & Wang, Y.J. (2002). “Peroxide formation in polysorbate 80 and protein stability.” Journal of Pharmaceutical Sciences, 91(10), 2252–2264.

10. Kerwin, B.A. (2008). “Polysorbates 20 and 80 used in the formulation of protein biotherapeutics: Structure and degradation pathways.” Journal of Pharmaceutical Sciences, 97(8), 2924–2935.

11. Garti, N., & Aserin, A. (1996). “Properties of polysorbates in oil-in-water emulsions.” Colloids and Surfaces A: Physicochemical and Engineering Aspects, 123–124, 233–246.

12. Schubert, M.A., & Müller-Goymann, C.C. (2003). “Characterisation of surfactants used in pharmaceutics and cosmetics: Polysorbates.” International Journal of Pharmaceutics, 261(1–2), 99–107.

13. Kishore, R.S.K., et al. (2011). “The degradation of polysorbates 20 and 80 and its impact on monoclonal antibody formulations.” Pharmaceutical Research, 28, 1194–1210.

Aladdin: https://www.aladdinsci.com/