J. Phys. II France
Volume 2, Number 8, August 1992
Page(s) 1563 - 1575
DOI: 10.1051/jp2:1992222
J. Phys. II France 2 (1992) 1563-1575

Fluctuations and stability of polymerized vesicles

Shigeyuki Komura1 and Reinhard Lipowsky2

1  Department of Physics, Faculty of Science, Kyoto University, Kyoto 606, Japan
2  Institut für Festkörperforschung, Forschungszentrum Jülich, D-5170 Jülich, Germany

(Received 30 April 1992, accepted 13 May 1992)

The shape fluctuations and the stability of polymerized vesicles are investigated within the framework of shell theory. The intrinsic curvature of the vesicle leads to an enhanced coupling between bending and stretching modes which acts to suppress the shape fluctuations on large scales. This effect is explicitly calculated for a cylindrical shape of the vesicle. For a cylinder with radius r0, the shape fluctuations exhibit the crossover scale $L^*\simeq (r_0^2\kappa /Y)^{1/4}$, where $\kappa$ and Y are the bending rigidity and the (2-dimensional) Young modulus of the polymerized membrane. For $L\ll L^*$, the fluctuations are fluid-like but are strongly suppressed for $L\gg L^*$. In addition, the stability of the cylinder with respect to an external pressure is studied, and a sequence of critical pressure values is determined at which the cylinder becomes unstable.

05.40 - 87.22

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