Dynamical and conformational behavior of a polymer in a crowded solution
Abstract
We investigate the structure and dynamics of a polymer in a fluid containing mobile spherical colloidal crowders of radius R. We compare and contrast the behavior with Langevin dynamics (LD) and lattice--Boltzmann molecular dynamics (LBMD), the latter incorporating long-range hydrodynamic interactions. Both the colloid size relative to the monomer radius r and the volume fraction ϕ are varied to determine how crowding modifies polymer behavior. Increasing volume fraction induces polymer compaction, with the mechanism strongly dependent on the size ratio R/r. Small colloids primarily modify the short-wavelength polymer conformation, causing self-avoiding-walk-like behavior to persist to shorter length scales, whereas large colloids reduce the effective long-wavelength Flory exponent, indicating degraded solvent quality consistent with a confinement-blob picture. Polymer diffusion exhibits distinct behavior in LD and LBMD. In LD, diffusion decreases rapidly and depends strongly on R/r; a phenomenological scaling involving ln(1+R/r) captures this size dependence, and additional scaling with Rg reduces scatter, indicating polymer-scale correlations induced by crowding. In contrast, LBMD diffusion follows an effective-medium-like exponential dependence on concentration, governed by hydrodynamic coupling. Rouse-mode analysis identifies three regimes: scaling breakdown at low volume fraction, Zimm-like behavior at intermediate density in both LD and LB, and at high density hydrodynamic screening in LB with confinement-dominated dynamics in LD.
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BibTeX
@misc{changizrezaei2026dynamical,
title = {{Dynamical and conformational behavior of a polymer in a crowded solution}},
author = {Setarehalsadat Changizrezaei and Colin Denniston},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2608.25242},
eprint = {2608.25242},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.25242},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Dynamical and conformational behavior of a polymer in a crowded solution
AU - Setarehalsadat Changizrezaei
AU - Colin Denniston
PY - 2026
DA - 2026/08/27
PB - arXiv
DO - 10.48550/arxiv.2608.25242
UR - https://arxiv.org/abs/2608.25242
AB - We investigate the structure and dynamics of a polymer in a fluid containing mobile spherical colloidal crowders of radius R. We compare and contrast the behavior with Langevin dynamics (LD) and lattice--Boltzmann molecular dynamics (LBMD), the latter incorporating long-range hydrodynamic interactions. Both the colloid size relative to the monomer radius r and the volume fraction ϕ are varied to determine how crowding modifies polymer behavior. Increasing volume fraction induces polymer compaction, with the mechanism strongly dependent on the size ratio R/r. Small colloids primarily modify the short-wavelength polymer conformation, causing self-avoiding-walk-like behavior to persist to shorter length scales, whereas large colloids reduce the effective long-wavelength Flory exponent, indicating degraded solvent quality consistent with a confinement-blob picture. Polymer diffusion exhibits distinct behavior in LD and LBMD. In LD, diffusion decreases rapidly and depends strongly on R/r; a phenomenological scaling involving ln(1+R/r) captures this size dependence, and additional scaling with R_g reduces scatter, indicating polymer-scale correlations induced by crowding. In contrast, LBMD diffusion follows an effective-medium-like exponential dependence on concentration, governed by hydrodynamic coupling. Rouse-mode analysis identifies three regimes: scaling breakdown at low volume fraction, Zimm-like behavior at intermediate density in both LD and LB, and at high density hydrodynamic screening in LB with confinement-dominated dynamics in LD.
ER -