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The hydrophilic–lipophilic balance (HLB) of a surfactant is a measure of its degree of
hydrophilicity A hydrophile is a molecule or other molecular entity that is attracted to water molecules and tends to be dissolved by water.Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon'' Oxford: Clarendon Press. In contrast, hydrophobes are no ...
or
lipophilicity Lipophilicity (from Greek λίπος "fat" and φίλος "friendly"), refers to the ability of a chemical compound to dissolve in fats, oils, lipids, and non-polar solvents such as hexane or toluene. Such non-polar solvents are themselves lipo ...
, determined by calculating percentages of molecular weights for the hydrophilic and lipohilic portions of the surfactant molecule, as described by Griffin in 1949 and 1954. Other methods have been suggested, notably in 1957 by Davies.


Griffin's method

Griffin's method for non-ionic surfactants as described in 1954 works as follows: HLB = 20 * M_h / M where M_h is the
molecular mass The molecular mass (''m'') is the mass of a given molecule: it is measured in daltons (Da or u). Different molecules of the same compound may have different molecular masses because they contain different isotopes of an element. The related quanti ...
of the hydrophilic portion of the molecule, and M is the molecular mass of the whole molecule, giving a result on a scale of 0 to 20. An HLB value of 0 corresponds to a completely lipophilic/hydrophobic molecule, and a value of 20 corresponds to a completely hydrophilic/lipophobic molecule. The HLB value can be used to predict the surfactant properties of a molecule: * < 10 : Lipid-soluble (water-insoluble) * > 10 : Water-soluble (lipid-insoluble) * 1 to 3: anti-foaming agent * 3 to 6: W/O (water in oil) emulsifier * 7 to 9: wetting and spreading agent * 13 to 16: detergent * 8 to 16: O/W (oil in water) emulsifier * 16 to 18: solubiliser or hydrotrope


Davies' method

In 1957, Davies suggested a method based on calculating a value based on the chemical groups of the molecule. The advantage of this method is that it takes into account the effect of stronger and weaker hydrophilic groups. The method works as follows: HLB = 7 + \sum_^H_i - n \times 0.475 where: m - Number of hydrophilic groups in the molecule H_i - Value of the ith hydrophilic groups (see tables) n - Number of lipophilic groups in the molecule


References

{{DEFAULTSORT:Hydrophilic-Lipophilic Balance Surfactants