# Compressive response and helix formation of a semi flexible polymer confined in a nanochannel

## TL;DR

This study investigates how a semi-flexible polymer confined in a nanochannel undergoes structural transitions, including helix formation, when compressed, revealing buckling as a key mechanism and noting the rapid onset of helix formation.

## Contribution

The paper introduces a detailed numerical analysis of structural transitions and helix formation in a semi-flexible polymer under compression within nanochannels, highlighting buckling as the underlying process.

## Key findings

- Polymer undergoes multiple structural transitions under compression.
- Helix formation occurs at very small compression levels.
- Buckling of deflection segments explains helix transition.

## Abstract

Configurations of a single semiflexible polymer is studied when it is pushed into a nanochannel in the case where the polymer persistence length $l_p$ is much longer than the channel diameter $D$, i.e. $l_p/D \gg 1$. Using numerical simulations, we show that the polymer undergoes a sequence of recurring structural transitions upon longitudinal compression, i.e. random deflection along the channel, helix going around the channel wall, double-fold random deflection, double-fold helix, etc. We find that the helix transition can be understood as buckling of deflection segments, and the initial helix formation takes place at very small compression with no appreciable weak compression regime of the random deflection polymer.