Entry by Andrew Capulli
HLB Scale: Hydrophilic-Lipophilic Balance
Developed by Griffin (1949), the HLB Scale ranks the tendency of a surfactant to be hydrophilic or hydrophobic (lipophilic). Since a surfactant molecule has both hydrophilic and hydrophobic portions (that's why its a surfactant!) Griffin developed a ranking system to determine 'how hydrophilic' and 'how hydrophobic' a surfactant is. Surfactants generally have hydrophobic hydrocarbon chains with hydrophilic branches or ends (this scale is for non-ionic surfactants). The HLB scale is very relative scale; the number values of the HLB Scale don't necessarily give insight into the properties of a surfactant, just their relative hydrophilicity compared to other surfactants. That said, the HLB Scale is widely used in industry.
- The HLB Scale ranges 1-20
- Surfactants with higher HLB numbers (greater than 10) are more hydrophilic
- Surfactants with lower HLB number (less than 10) are more hydrophobic (lipophilic)
Higher HLB Scale valued surfactants are more hydrophilic and thus are more water soluble. Similarly, lower HLB Scale valued surfactants are more lipophilic and thus more oil soluble. So, higher HLB surfactants will created oil-in-water emulsions and lower HLB surfactants will create water-in-oil emulsions: