Effect of Aromatic Ring in the Alkyl Chain on Surface Properties of Aryl Alkyl Sulfonate Surfactants

Abstract Surface properties of a series of aryl alkyl sulfonate surfactants were investigated. A strong structure-activity relationship was observed, depending on the variation of aromatic ring size in the hydrophobic chain. The results show that the size of aromatic ring, introduced to the carbon chain, affects their surface and thermodynamic properties. The values of critical micelle concentration (cmc), surface excess concentration (Γmax), effectiveness (Πcmc), to reduce surface tension of water, are decreased with increasing the aromatic ring size from phenyl to methylnaphthyl. While, the values of surface tension (γcmc) at cmc, Gibbs energy of micellization (ΔGmic°), and minimum area per molecule (Amin) are increased. Hence, the dominant factor of influencing on the area per molecule of aryl alkyl sulfonate surfactants would be the size of aryl alkyl chains.