Sphere to cylinder transition in a single phase microemulsion system: A theoretical investigation

The sphere to cylinder transition in a one-phase droplet microemulsion syst em is studied theoretically. Within the framework of the curvature energy m odel by Helfrich, it was already shown by Safran [J. Phys. (France) Lett. 4 5, L-69 (1984)] that for a certain range of the curvature parameters (rigid ity constants and spontaneous curvature), a transition occurs from spherica l droplets to infinitely long cylinders through a region where both spheres and cylinders are present. Our aim is to further investigate this region i n a quantitative way by including-in addition to curvature energy-translati on entropy, cylinder length polydispersity, and radial polydispersity. In t his way we are able to obtain structural information on the spheres and cyl inders formed, their respective volume fractions, and polydispersity, and p rovide a more detailed comparison with experimental results. (C) 2001 Ameri can Institute of Physics.