Is Polysorbate 20 natural?

Sorbitol from corn starch dehydrated to sorbitan, esterified with coconut lauric acid, then ethoxylated with 20 mol petrochemical ethylene oxide.

The synthesis of Polysorbate 20 involves a multi-step process. First, sorbitol, a sugar alcohol, is dehydrated to form sorbitan. This dehydration is typically carried out under vacuum at elevated temperatures (around 150-200°C), often with the aid of an acid catalyst, to remove water molecules and form cyclic ethers.

Following the formation of sorbitan, it undergoes ethoxylation. This reaction involves reacting sorbitan with ethylene oxide (EO) in the presence of a basic catalyst, such as potassium hydroxide (KOH) or sodium hydroxide (NaOH). The reaction is typically conducted in a closed reactor under pressure and at temperatures ranging from 120-180°C. Ethylene oxide molecules add sequentially to the hydroxyl groups of the sorbitan molecule.

For Polysorbate 20, an average of 20 moles of ethylene oxide are added per mole of sorbitan. The degree of ethoxylation is controlled by the molar ratio of ethylene oxide to sorbitan used in the reaction. After the ethoxylation is complete, the catalyst is neutralized, and the product is purified. Purification steps may include filtration, vacuum stripping to remove unreacted ethylene oxide and byproducts, and sometimes decolorization with activated carbon.

The final product is a mixture of ethoxylated sorbitan esters, with Polysorbate 20 specifically referring to the esterification of sorbitan ethoxylated with approximately 20 moles of ethylene oxide. The esterification step itself is not part of the Polysorbate 20 synthesis but rather the subsequent reaction to form specific polysorbate esters (e.g., Polysorbate 20 is the laurate ester of ethoxylated sorbitan). However, the term Polysorbate 20 often refers to the ethoxylated sorbitan itself, which acts as a non-ionic surfactant.

Polysorbate 20 is a common ingredient used in cosmetics and personal care products, primarily acting as an emulsifier and solubilizer. Think of it as a helper molecule that allows oil and water-based ingredients, which normally don't mix, to blend together smoothly. This is crucial for creating stable lotions, creams, and serums.

It's made through a process that combines ingredients from both nature and the petrochemical industry. The 'sorbitan' part comes from sorbitol, a sugar alcohol derived from plant starches like corn. The 'ethoxylated' part involves reacting this with ethylene oxide, a chemical typically made from fossil fuels. Because it uses a mix of renewable and petroleum-based sources, it's considered 'half renewable' under the ISO 16128 standard.

CosIng definition: Sorbitan, monododecanoate, poly(oxy-1,2-ethanediyl) derivs.