The Selective Binding of Anions to Gemini and Trimeric Surfactants at Air/Solution Interfaces

The selective binding of Br–, Cl–, I–, NO3–, and salicylate anions to quaternary ammonium gemini and trimer surfactant solution/air interfaces has been studied by ion flotation, examining the effect of the degree of oligomerization and polymethylene spacer length between the quaternary nitrogen atoms. The binding of the halides and nitrate showed no significant change with degree of oligomerization. However, salicylate showed a marked decrease in selective uptake with increasing degree of oligomerization, and increased with increasing spacer length.