Polysorbate 21 (Tween 21) – Low-EO Wetting Agent & Emulsifier

Overview

Chemical Nature

Specialized non-ionic surfactant with lower ethylene oxide content (4 moles) compared to Tween 20.
Appearance & Specs

Yellow liquid | HLB Value: 13.3
★ Primary Application (Industrial)

Superior Wetting Agent. Offers unique spreading capabilities where standard solubilizers fail. Ideal for coatings, agrochemicals, and specialized emulsions.
Vs. Standard Tweens

Lower EO content provides distinct wetting properties different from high-mole polysorbates.
Key Functions

Wetting agent & Industrial Emulsifier.

Molecular Structure

Structural Components

Hydrophilic Segment: Sorbitan (sorbitol-derived) backbone attached to 4 ethylene oxide units.

Hydrophobic Moiety: A lauric acid ester group serving as the lipophilic segment.
★ Mechanism of Action

Interface Orientation. This specific amphiphilic structure allows it to orient precisely between oil and water phases. It is particularly effective at stabilizing emulsions and improving the dispersion of lipophilic substances in aqueous systems.

Specifications：

Owing to its balanced structure, Polysorbate 21 shows moderate hydrophilicity and good compatibility with other surfactants. It serves as a versatile emulsifier and solubilizer in food applications, where stable dispersion and mild processing conditions are required.

Test Item	Unit	Min Value	Max Value
HLB value	——	15.6
Saponification Value	mgKOH/g	100	115
Iodine Value	mgKOH/g	225	255
Acid Value	mgKOH/g	—	2
Moisture	%	—	3

Download TDS

Applications：

Agrochemicals & Industrial Formulations Polysorbate 21 is primarily utilized as a high-performance wetting agent and spreading adjuvant. Unlike standard solubilizers, its unique chemical structure (containing only 4 moles of Ethylene Oxide) provides rapid surface tension reduction. It is the preferred choice for agrochemical sprays, industrial coatings, and specialized drilling fluids where superior spreading capabilities are required.

Superior Wetting Agent

With a shorter EO chain, Polysorbate 21 reduces surface tension more effectively than Tween 20, allowing liquids to spread rapidly across difficult surfaces (like leaves or coated metals).

Controlled Solubility (HLB 13.3)

Provides a balanced HLB of 13.3, bridging the gap between oil-soluble Spans and high-HLB Tweens. Perfect for stabilizing complex micro-emulsions.

Industrial & Agrochemical Use

Widely used in crop protection formulations to help pesticides adhere to plant leaves, and in industrial coatings for pigment dispersion.

Low Foaming

Generates less foam than higher-EO counterparts, making it easier to process in high-speed mixing equipment.

Macro shot of a liquid droplet spreading flat on a waxy green leaf, demonstrating the superior wetting agent properties of Polysorbate 21 in agrochemical sprays.

Uniform blue pigment dispersion in a laboratory beaker, highlighting the stabilizer and dispersant capabilities of Polysorbate 21 for industrial coatings and inks.

storage & package：

Storage:
Store in a cool, dry, and well-ventilated area, away from direct sunlight and sources of heat.
Avoid contact with harmful or incompatible substances. Handle with care during transportation to prevent leakage or contamination.

Transportation:
Transport as a general chemical product, following standard safety and handling procedures.

Package:
Polysorbate 21 is packed in high-quality PE drums with double-seal lids.
Standard packaging sizes include 25kg/drum, 200kg/drum, and 1000kg IBC tote to meet different usage needs.