Definition
The HLB scale is a numerical system that indicates the balance between the hydrophilic and lipophilic portions of a surfactant molecule.
Scale Range: 0 (completely lipophilic) to 20 (completely hydrophilic).
Calculation
For nonionic surfactants:
where:
M_hydrophilic is the molecular mass of the hydrophilic portion.
M_Total is the total molecular mass of the surfactant.
Applications of Hydrophile-Lipophile Balance (HLB) Scale
Emulsion Type Determination:
O/W Emulsions: Surfactants with HLB values of 8-18.
W/O Emulsions: Surfactants with HLB values of 3-6.
Formulation Optimization: Selecting appropriate surfactants for desired properties.
Solubilizers and Detergents: High HLB surfactants are effective solubilizers.
Blending Surfactants
Surfactants can be blended to achieve a desired HLB value.
Equation:
where:
fA and fB are the weight fractions of surfactants A and B.