Hydrophile-lipophile balance of alkyl ethoxylated surfactants as a function of intermolecular energies.

The semiempirical MNDO method has been used in order to examine the variation of the molecular properties of hydrocarbons CnH2n + 2 (with 1 < or = n < or = 19) and ethylene oxide chains CH3(CH2CH2O)mCH3 (with 1 < or = m < or = 19) as a function of their molecular length. Least-square fits of those properties have been calculated, along with two mathematical relations between the hydrophile-lipophile balance of alkyl-phenol ethoxylated surfactants and (1) the ratio of molecular lengths between their lipophilic and hydrophilic branches; (2) the intermolecular energies between the molecules of surfactant, water and hexane.