Influence of Temperature on the Surface Tension of Triton Surfactant Solutions

Abstract The surface tension of different Triton surfactants (X‐100, X‐405, and X‐705) with or without adding sodium chloride was measured in the temperature range between 20 and 40°C using the maximum bubble pressure method. Rising temperature reduced the surface tension of Triton surfactants via disrupting the H‐bonds between the ethylene oxide (EO) group and water. Increasing the number of the EO groups created the steeper thermal gradient of the surface tension. The data indicated that EO‐water bonds are easier to be broken by rising temperature than the water–water H‐bonds, with an entropy change of −0.535 J deg −1 per mole of EO. The presence of NaCl decreased the surface tension for all systems. However, NaCl produced a synergistic effect with surfactants on the surface tension.