Elongation and fluctuations of semi-flexible polymers in a nematic solvent

TL;DR

This study visualizes semi-flexible polymers in a nematic solvent, revealing a coil-rod transition and how nematic fluctuations influence polymer behavior, while quantifying key physical parameters.

Contribution

It provides direct visualization and quantitative analysis of polymer elongation, fluctuations, and phase transitions in a nematic environment, including extraction of elastic properties.

Findings

Polymers with large persistence length undergo a coil-rod transition.

Transverse fluctuations are driven by nematic background fluctuations.

Odijk deflection length and elastic constant are quantitatively extracted.

Abstract

We directly visualize single polymers with persistence lengths ranging from $\ell_p=0.05$ to 16 $\mu$m, dissolved in the nematic phase of rod-like {\it fd} virus. Polymers with sufficiently large persistence length undergo a coil-rod transition at the isotropic-nematic transition of the background solvent. We quantitatively analyze the transverse fluctuations of semi-flexible polymers and show that at long wavelengths they are driven by the fluctuating nematic background. We extract both the Odijk deflection length and the elastic constant of the background nematic phase from the data.