Polysorbate 80 is a nonionic ingredient compatible with both anionic and cationic surfactants. With an HLB value of 15, it functions as a strong hydrophilic emulsifier for oil-in-water (O/W) emulsions, although its more common application is the solubilization of essential oils. Owing to its long ethoxylated chain, it also helps reduce the irritation typically associated with sulfate surfactants, making it valuable in the development of mild personal care formulations.
Its structure, which includes approximately 20 ethylene oxide units, one sorbitol molecule, and one oleic acid moiety as the primary fatty acid, gives it an estimated molecular weight of 1310 daltons. The presence of oleic acid increases hydrophobicity (resulting in a lower HLB value) and improves the solubilization of lipophilic substances compared to Polysorbate 20. Its critical micelle concentration (CMC) falls within the range of 13 to 15 ppm.
Polysorbate 80 belongs to the broader Polysorbate family, differing mainly in the type of fatty acid used in its composition:
- Polysorbate 20: PEG-20 sorbitan monolaurate
- Polysorbate 40: PEG-20 sorbitan monopalmitate
- Polysorbate 60: PEG-20 sorbitan monostearate
- Polysorbate 80: PEG-20 sorbitan monooleate
This material exhibits little to no intrinsic antibacterial activity, but it has been shown to reduce the effectiveness of methyl paraben and similar compounds*.
* Patel N., Kostenbauder H. Journal of the American Pharmaceutical Association 2006, 47, 4, p. 289-93.
