DEFORMABILITY OF LAMELLAR DROPLETS

The deformability has been calculated of a lamellar droplet, consisting of concentric surfactant bilayers, separated by water. The deformation energy of the droplet is expressed in terms of the bending modulus kappa of each bilayer and the bulk compressibility modulus, B, which is directly correlated to the interaction between the layers. The expression for the deformation energy has subsequently been used to derive an effective surface tension of the droplet. For ellipsoidal deformations, this surface tension is of the same order of magnitude as that found by De Gennes for a planar stack of bilayers. Even if the bilayers themselves do not exhibit surface tension, there still is an effective surface tension, sigma(eff), due to the bulk properties of the lamellar phase, in the order of 0.01-1 mN/m.