Thermal fluctuations and stiffening of heterogeneous fluid membranes

TL;DR

This paper investigates how thermal fluctuations influence the stiffness of heterogeneous fluid membranes near critical points, revealing that fluctuations can enhance membrane rigidity contrary to behavior in pure membranes.

Contribution

It introduces a minimal model showing that thermal fluctuations can increase the effective bending modulus of heterogeneous membranes near criticality.

Findings

Thermal fluctuations suppress membrane fluctuations near critical temperature.

Heterogeneous membranes exhibit increased stiffness close to the phase transition.

Contrast with pure membranes where fluctuations always reduce stiffness.

Abstract

We study the effects of thermal fluctuations on symmetric tensionless heterogeneous (two-component) fluid membranes in a simple minimal model. Close to the critical point $T_c$ of the associated miscibility phase transition of the composition and for sufficiently strong curvature-composition interactions, mediated through a composition-dependent bending modulus, thermal fluctuations lead to enhancement of the effective bending modulus. Thus, the membrane conformation fluctuations will be {\em suppressed} near $T_c$, in comparison with a pure fluid membrane, for which thermal fluctuations are known to reduce the effective bending modulus at all non-zero temperatures.