Membranes in rod solutions: a system with spontaneously broken symmetry

TL;DR

This paper investigates how rod-like particles in dilute solutions influence membrane curvature and elasticity, revealing that exposure to rods can induce spontaneous curvature and exploring confinement effects in curved geometries.

Contribution

It demonstrates that rod depletion layers can induce spontaneous membrane curvature and extends the analysis to rigid disks and confined geometries, linking to quantum and polymer systems.

Findings

Rod depletion layers induce spontaneous membrane curvature.

Exposure to rods on both sides causes curvature.

Confinement in shells affects rod behavior and membrane properties.

Abstract

We consider a dilute solution of infinitely rigid rods near a curved, perfectly repulsive surface and study the contribution of the rod depletion layer to the bending elastic constants of membranes. We find that a spontaneous curvature state can be induced by exposure of BOTH sides of the membrane to a rod solution. A similar result applies for rigid disks with a diameter equal to the rod's length. We also study the confinement of rods in spherical and cylindrical repulsive shells. This helps elucidate a recent discussion on curvature effects in confined quantum mechanical and polymer systems.