Shapes of hydrophobic thick membranes

TL;DR

This paper investigates the phase behavior and conformations of hydrophobic thick membranes in three dimensions, revealing distinct folding mechanisms and symmetry-breaking phenomena depending on solvent size.

Contribution

It introduces a model for thick membranes with hydrophobic interactions and analyzes their phase transitions and folding behavior in different solvent regimes.

Findings

Membranes fold along a preferential axis with small solvents.

Large solvents induce local crinkling to shield the membrane.

A transition exists between membrane binding and unbinding from a wall.

Abstract

We introduce and study the behavior of a tethered membrane of non-zero thickness embedded in three dimensions subject to an effective self-attraction induced by hydrophobicity arising from the tendency to minimize the area exposed to a solvent. The phase behavior and the nature of the folded conformations are found to be quite distinct in the small and large solvent size regimes. We demonstrate spontaneous symmetry-breaking with the membrane folding along a preferential axis, when the solvent molecules are small compared to the membrane thickness. For large solvent molecule size, a local crinkling mechanism effectively shields the membrane from the solvent, even in relatively flat conformations. We discuss the binding/unbinding transition of a membrane to a wall that serves to shield the membrane from the solvent.