Entropic alignment of topologically modified ring polymers in cylindrical confinement

Fuente: arXiv
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Main Authors: Bhandarkar, Sanjay, Mitra, Debarshi, Horbach, Jürgen, Chatterji, Apratim
Format: Preprint
Published: 2025
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author Bhandarkar, Sanjay
Mitra, Debarshi
Horbach, Jürgen
Chatterji, Apratim
author_facet Bhandarkar, Sanjay
Mitra, Debarshi
Horbach, Jürgen
Chatterji, Apratim
contents Under high cylindrical confinement, segments of ring polymers can be localized along the long axis of the cylinder by introducing internal loops within the ring polymer. The emergent organization of the polymer segments occurs because of the entropic repulsion between internal loops. These principles were used to identify the underlying mechanism of bacterial chromosome organization. Here, we outline functional principles associated with entropic interactions, leading to specific orientations of the ring polymers relative to their neighbors in the cylindrical confinement. We achieve this by modifying the ring polymer topology by creating internal loops of two different sizes within the polymer, and thus create an asymmetry. This allows us to strategically manipulate polymer topology such that segments of a polymer face certain other segments of a neighboring polymer. The polymers therefore behave as if they are subjected to an `effective' entropic interaction reminiscent of interactions between Ising spins. But this emergent spatial and orientational organization is not enthalpy-driven. We consider a bead spring model of flexible polymers with only repulsive excluded volume interactions between the monomers. The polymers entropically repel each other and occupy different halves of the cylinder, and moreover, the adjacent polymers preferentially re-orient themselves along the axis of the cylinder. We further substantiate our observations by free energy calculations. To the best of our knowledge, this is the first study of the emergence of effective orientational interactions by harnessing entropic interactions in flexible polymers. The principles elucidated here could be relevant to understand the interactions between different sized loops within a large chromosome.
format Preprint
id arxiv_https___arxiv_org_abs_2511_12813
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Entropic alignment of topologically modified ring polymers in cylindrical confinement
Bhandarkar, Sanjay
Mitra, Debarshi
Horbach, Jürgen
Chatterji, Apratim
Soft Condensed Matter
Under high cylindrical confinement, segments of ring polymers can be localized along the long axis of the cylinder by introducing internal loops within the ring polymer. The emergent organization of the polymer segments occurs because of the entropic repulsion between internal loops. These principles were used to identify the underlying mechanism of bacterial chromosome organization. Here, we outline functional principles associated with entropic interactions, leading to specific orientations of the ring polymers relative to their neighbors in the cylindrical confinement. We achieve this by modifying the ring polymer topology by creating internal loops of two different sizes within the polymer, and thus create an asymmetry. This allows us to strategically manipulate polymer topology such that segments of a polymer face certain other segments of a neighboring polymer. The polymers therefore behave as if they are subjected to an `effective' entropic interaction reminiscent of interactions between Ising spins. But this emergent spatial and orientational organization is not enthalpy-driven. We consider a bead spring model of flexible polymers with only repulsive excluded volume interactions between the monomers. The polymers entropically repel each other and occupy different halves of the cylinder, and moreover, the adjacent polymers preferentially re-orient themselves along the axis of the cylinder. We further substantiate our observations by free energy calculations. To the best of our knowledge, this is the first study of the emergence of effective orientational interactions by harnessing entropic interactions in flexible polymers. The principles elucidated here could be relevant to understand the interactions between different sized loops within a large chromosome.
title Entropic alignment of topologically modified ring polymers in cylindrical confinement
topic Soft Condensed Matter
url https://arxiv.org/abs/2511.12813