Chemically Talking, this molecule is "midway" among Sorbitan Oleate and Sorbitan Trioleate, indicating that it is also an attachment of sorbitan (a dehydrated sorbitol (sugar) molecule) with the unsaturated fatty acid Oleic Acid, but inside of a ratio of two:3 hence the "Sesqui" part inside the molecule's title. It may purpose like a wetting a