Entropy driven formation of a chiral liquid crystalline phase of helical filaments

TL;DR

This study investigates how concentrated suspensions of helical bacterial flagella undergo an entropy-driven phase transition to a novel chiral liquid crystalline state, highlighting the influence of filament shape and chirality.

Contribution

It demonstrates the formation of a unique chiral liquid crystalline phase in helical filaments, driven by entropy, and compares behavior with achiral rods.

Findings

Helical flagella exhibit a first-order phase transition to a chiral liquid crystalline phase.

The phase behavior and dynamics differ significantly from achiral rods.

The resulting phase has a novel chiral symmetry.

Abstract

We study the liquid crystalline phase behavior of a concentrated suspension of helical flagella isolated from {\it Salmonella typhimurium}. Flagella are prepared with different polymorphic states, some of which have a pronounced helical character while others assume a rod-like shape. We show that the static phase behavior and dynamics of chiral helices are very different when compared to simpler achiral hard rods. With increasing concentration, helical flagella undergo an entropy driven first order phase transition to a liquid crystalline state having a novel chiral symmetry.