Surface flow of surfactant layer on air/water interface

This study shows that a heat gradient can produce a surface flow on a surfactant layer. The flow was directly observable via a movement of a floating Teflon ball. A model was developed to quantify the driving force. The model indicated that the movement was generated by the local tension on the surfactant layer and adhesion between Teflon and the layer. The phenomenon is similar to Marangoni effect, but it is more applicable for industrial surfactants. In particular, the thermal-generated surface flow can open up a new avenue to manipulate the thermal response of the surfactant layer.