DOI: 10.1051/jp2:1997199
J. Phys. II France 7 (1997) 1509-1520

Sponges, Tubules and Modulated Phases of Para-Antinematic Membranes

J.B. Fournier¹ and P. Galatola<sup>2

1</sup>  Laboratoire de Physico-Chimie Théorique, École Supérieure de Physique et de Chimie Industrielles de la Ville de Paris, 10 rue Vauquelin, 75231 Paris Cedex 05, France
²  Dipartimento di Fisica, Politecnico di Torino, and Istituto Nazionale di Fisica della Materia, C.so Duca degli Abruzzi 24, 10129 Torino, Italy

(Received 11 February 1997, revised 28 May 1997, accepted 5 June 1997)

Abstract
We theoretically analyze the behavior of membranes presenting a nematic susceptibility, induced by the presence of anisotropic phospholipids having a quadrupolar nematic symmetry. This kind of anisotropic phospholipids is either naturally found in some biological membranes, or can be chemically tailored by linking pairs of single surfactants at the level of their polar heads, giving rise to so-called "gemini" surfactants. We predict that such membranes can acquire a non-zero paranematic order induced by the membrane curvature, which in turn produces curvature instabilities. We call the resulting paranematic order para-antinematic, since it is opposite on opposite sides of the membrane. We find phase transitions toward sponges (L ₃), tubules, or modulated "egg-carton" phases.

© Les Editions de Physique 1997