Phase diagram and effective shape of semi-flexible colloidal rods and biopolymers

TL;DR

This paper models semi-flexible colloidal rods and biopolymers to predict phase behavior and effective shapes, achieving quantitative agreement with experiments and highlighting the importance of stiffness in system properties.

Contribution

It introduces a segmented-chain model using an Onsager-type functional to accurately predict phase diagrams and effective shapes of semi-flexible rods and biopolymers.

Findings

Phase diagrams match experimental data quantitatively.

Effective shapes are shorter and thicker than actual shapes.

Stiffness significantly influences system behavior.

Abstract

We study suspensions of semi-flexible colloidal rods and biopolymers using an Onsager-type second-virial functional for a segmented-chain model. For suspensions of thin and thick fd virus particles we calculate phase diagrams in quantitative agreement with experimental observations, and we find their effective state-point dependent shape to be much shorter and thicker than the actual shape. We also calculate the stretching of worm-like micelles in a host fd virus solution, again finding agreement with experiments. For both systems, our results show that the fd virus stiffness can play a key role in system behavior.