CRITICAL BEHAVIOR OF VESICLES AND MEMBRANES

Abstract
Recent theoretical work on the critical behavior of vesicles and membranes is reviewed. Vesicles can exhibit a wide variety of different shapes and shape transformations which can be continuous or discontinuous. In the presence of an attractive surface, a vesicle can undergo shape transformations between two different free states, between a free and a bound state, and between two different bound states. In solution, membranes undergo shape fluctuations on many length scales which are characterized by the roughness exponent ζ. For polymerized membranes, ζ = 1/2 has been obtained from scaling arguments and Monte Carlo simulations. In contrast to previous simulations, Our Monte Carlo data are consistent with a finite value of the shear modulus on large scales. The shape fluctuations affect the adhesion of membranes and lead to unbinding transitions. Detailed renormalization group studies show that both fluid and polymerized membranes unbind in a continuous manner for sufficiently short-ranged interactions.