Hydrophilic-lipophilic balance

The Hydrophilic-lipophilic balance of a surfactant is a measure of the degree to which it is hydrophilic or lipophilic, determined by calculating values for the different regions of the 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 * Mh / M

where Mh is the molecular mass of the hydrophilic portion of the Molecule, and M is the molecular mass of the whole molecule, giving a result on an arbitrary scale of 0 to 20. An HLB value of 0 corresponds to a completely hydrophobic molecule, and a value of 20 would correspond to a molecule made up completely of hydrophilic components.

The HLB value can be used to predict the surfactant properties of a molecule:

• A value < 10 : Lipid soluble (water insoluble)
• A value > 10 : Water soluble
• A value from 4 to 8 indicates an anti-foaming agent
• A value from 7 to 11 indicates a W/O (water in oil) emulsifier
• A value from 12 to 16 indicates oil in water emulsion
• A value from 11 to 14 indicates a wetting agent
• A value from 12 to 15 is typical of detergents
• A value of 16 to 20 indicates a 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 strongly and less strongly hydrophilic groups. The method works as follows:

HLB = 7 + m * Hh − n * Hl

with:

m - Number of hydrophilic groups in the molecule

Hh - Value of the hydrophilic groups

n - Number of lipophilic groups in the molecule

Hl - Value of the lipophilic groups