We investigate the formation of $\mathsf{Y}$ junctions in surfactant nanotubes connecting vesicles. Based on experimental observations of the surfactant flow on the nanotubes, we conclude that a $\mathsf{Y}$ 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 $\mathsf{Y}$ junction dynamics that is in quantitative agreement with the experimental data.

• Received 11 April 2006
• Corrected 7 November 2006

DOI:https://doi.org/10.1103/PhysRevLett.97.188105