Self-Assembly of Crowded Semiflexible Polymers under Dynamic and Deformable Confinement

TL;DR

This study uses simulations to explore how semiflexible polymers self-assemble within deformable, dynamically changing droplets, revealing how confinement rate, polymer length, and concentration influence structural organization.

Contribution

It introduces a systematic analysis of polymer self-assembly under deformable, time-evolving confinement, highlighting the interplay between polymer properties and dynamic environmental changes.

Findings

Higher polymer concentration leads to ordered fibrillar domains.

Intermediate chain lengths form maximally ordered fibrils.

Slow confinement increases structural order, rapid confinement traps disorder.

Abstract

Semiflexible polymers are ubiquitous in natural and artificial systems, where their intermediate rigidity gives rise to rich structural and dynamical behavior. Confinement plays a central role in these behaviors, as spatial restrictions can promote chain alignment, induce structural rearrangements, and enable complex self-assembly. While the organization of semiflexible polymers under rigid confinement has been extensively investigated, their behavior within deformable and dynamically evolving microenvironments, such as drying droplets or intracellular compartments, remains poorly understood. In this study, we use dissipative particle dynamics simulations to investigate the self-assembly of crowded semiflexible polymers confined within a deformable droplet, whose size may also change over time. By systematically varying polymer contour length, concentration, and degree of confinement, we identify distinct assembly regimes. Increasing polymer concentration promotes the formation of ordered fibrillar domains, with orientational alignment strongest near the droplet interface. Chain length critically dictates the morphology of assembled structures: short chains remain largely disordered, chains with intermediate lengths form linear fibrillar structures with maximal nematic order, and long chains assemble into circular bundles. Dynamic confinement further modulates the assembly through the competition between the rate of confinement change and polymer mobility. Slow increase in the degree of confinement allows polymers to reorganize into highly ordered structures, while rapid crowding kinetically traps the system in disordered states. Our findings elucidate how polymer mechanics and time-dependent confinement jointly govern the organization of semiflexible polymers in deformable, dynamic, and crowded environments.