Zipper dynamics of surfactant nanotube Y junctions.

We investigate the formation of Y junctions in surfactant nanotubes connecting vesicles. Based on experimental observations of the surfactant flow on the nanotubes, we conclude that a Y junction propagates with a zipperlike mechanism. The surfactants from two nanotube branches undergo 1:1 mixing at the junction, and spontaneously form the extension of the third nanotube branch. Taking into account the tension driven surfactant flow, we develop a model for the Y junction dynamics that is in quantitative agreement with the experimental data.