Spontaneous curvature-induced pearling instability

We investigate the instability of a tubular fluid membrane made of a water-soluble surfactant. The tubules are obtained at high brine salinities. The instability is due to introduction within the vesicle multilayer of an alkane. We measure the wavelength of this instability versus the unperturbed radius of the tubules and interpret this selection by using a model that includes not only the surface tension in the elastic energy, but also the effect of the asymmetry induced by the oil as a spontaneous curvature. The linear stability analysis shows that within this model the selection is indeed due to nonzero positive spontaneous curvature.