Summary: EUROPHYSICS LETTERS
Europhys. Lett., 19 (l),pp. 57-62 (1992)
1 May 1992
Equilibrium Shape of Two-Component Unilamellar
Membranes and Vesicles.
D.ANDELMAN(*)(**), T. KAWAKATSU(**)and K. KAWASAKI(**)
(*) School of Physics and Astronomy, Tel-Awiv University
Ramat Awiv 6997'8, Tel Aviv, Israel
(**I Department of Physics, Kyushu University 33 - Fukuoka 812, Japan
(received 3 September 1991; accepted in final form 30 March 1992)
PACS.87.20C - General theory of interfaces.
PACS.82.70K- Emulsions and suspensions.
PACS.64.60C - Order-disorder and statistical mechanics of model systems.
Abstract. -We show that a strong segregation of a two-component surfactant system coupled to
the local membrane curvature has a pronounced effect on the shape of unilamellae or closed
vesicles. For an average flat lamella, the preferred periodicity in the local composition as well as
the lamellar shape is calculated and depends on the ratio between surface tension and bending
modulus. In the case of a closed visicle with a futed total area, there is no selected periodicity in
contrast to the unilamellar case. For vesicles subjected to positive or negative inner pressure, we
calculate their shape numerically, whereas when there is no added inner pressure, the shape is