溶液中添加的苯磺酸钠(SNzS)和萘磺酸钠(SNphS)与C12-s-C12·2Br产生强烈结合,增大了Gemini表面活性剂分子的疏水性,明显促进其在气/液界面的吸附和在溶液中的聚集.这使得体系降低水表面张力的效率和能力大大提高,并且在表面活性剂浓度很低时就生成了小聚集体.因而,此时表面张力法测得的cmc仅具有表观上的意义,只反映了表面活性剂在气/液界面达到饱和吸附时的临界浓度.SNphS的疏水性强于SNzS,更有效地促进了C12-s-C12·2Br的吸附和聚集.
Sodium benzenesulfonate (SNzS) and sodium naphthalenesulfonate (SNphS) added in the solution strongly associated with quaternary ammonium gemini surfactants (C12-s-C12·2Br), which increased the hydrophobicity of C12-s-C12·2Br molecule and obviously enhanced their adsorption at the air/water interface and aggregation in the solution. This resulted in great increase in the efficiency and the effectiveness in surface tension reduction, and the formation of small aggregates in the solution at very low concentration of surfactant. Thus, the cmc obtained by surface tension method was only of apparent significance and it reflected the critical concentration when the surfactant reaching saturated adsorption at the air/water interface. Compared with SNzS, SNphS promoted more effectively both adsorption and aggregation of C12-s-C12·2Br due to its higher hydrophobicity.