Fluctuations and Defects in Lamellar Stacks of Amphiphilic Bilayers

TL;DR

This paper reviews molecular dynamics simulations of lamellar stacks of amphiphilic bilayers, demonstrating agreement with mesoscopic theories and providing insights into their mechanical properties and defects.

Contribution

It introduces an idealized coarse-grained model for amphiphile-solvent mixtures and validates mesoscopic theories against simulation results, including calculations of mechanical parameters.

Findings

Simulation results agree with mesoscopic theories.

Calculated line tension and mechanical moduli.

Discussed implications for polymer-membrane systems.

Abstract

We review recent molecular dynamics simulations of thermally activated undulations and defects in the lamellar $L_\alpha$ phase of a binary amphiphile-solvent mixture, using an idealized molecular coarse-grained model: Solvent particles are represented by beads, and amphiphiles by bead-and-spring tetramers. We find that our results are in excellent agreement with the predictions of simple mesoscopic theories: An effective interface model for the undulations, and a line tension model for the (pore) defects. We calculate the binding rigidity and the compressibility modulus of the lamellar stack as well as the line tension of the pore rim. Finally, we discuss implications for polymer-membrane systems.