THE INTERFACIAL BEHAVIOR OF NEW TYPES OF HYDROXYETHYLATED ALCOHOLS

Three series of novel hydroxyethylated surfactants were prepared from different precursors (phenylmethanol, beta-phenylethanol and gamma-phe nylpropanol) by using different catalysts (base (NaOH), Lewis-acid (Sn Cl4), and solid acid (K10 clay), respectively. The molecular weight di stributions of the products were determined and their interfacial beha viour was investigated at water-air and solid-water interfaces as a fu nction of surfactant concentration and of the average degree of hydrox yethylation. The samples, produced by acid catalysts, showed narrower molecular weight distribution and better surface activity (the ability to decrease surface tension) than those prepared by base catalyst. Th e effect of electrolyte concentration (NaCl) on the interfacial behavi our of surfactants was also studied. The presence of electrolyte in th e aqueous surfactant solutions resulted in significantly higher surfac e tensions land lower critical micelle concentrations) even at extreme low electrolyte concentrations (lower than 0.01 M), especially below the critical micelle concentration. The surface tension effects were i nterpreted in terms of the possible complex formation between the sodi um-ions and the surfactant molecules. The wettability measurements als o revealed better surface activity for the samples having narrower mol ecular weight distribution.