Peg- (inci)

"PEG" is the acronym for the thermoplastic "polyethylene glycol". Polyethylene glycols (syn. to macrogol) are chemically inert, water-soluble and non-toxic polymers (macromolecule of many low molecular weight monomers - basic building blocks) of the ethylene oxide (-CH2-CH2-O-)n-. Chemically, these are polyethers. The number 18 after "PEG-" (so-called code number) indicates the average number of ethylene oxide units, here 18 molecular units. The consistency of the PEG derivatives becomes more and more solid as the degree of polymerisation increases. PEGs with an average molecular weight up to 600 kg/mol are liquid, up to 1000 kg/mol waxy and from 4000 kg/mol solid, waxy.

PEG-18 is used in cosmetic formulations. The substance acts as a moisturizer (capable of increasing the water content of the skin) and as a solvent (capable of dissolving or diluting substances without causing chemical reactions between dissolved substance and dissolving agent).

1. Ammon HPT et al (2014) Hunnius Pharmaceutical Dictionary 11th Edition Walter de Gruyter Berlin-New York pp. 1437-1438