Tube Concept for Entangled Stiff Fibers Predicts Their Dynamics in Space and Time

TL;DR

This paper introduces a tube model for stiff fibers in crowded solutions, showing that their complex dynamics can be accurately predicted by simulating a single phantom needle with adjusted diffusion coefficients.

Contribution

The study develops a geometry-adapted simulation approach and demonstrates that the intermediate scattering function can be predicted from a single phantom needle model.

Findings

Accurate prediction of fiber dynamics using a single phantom needle model.

Development of a geometry-adapted neighbor list for simulations.

Quantitative agreement between simulations and theoretical predictions.

Abstract

We study dynamically crowded solutions of stiff fibers deep in the semidilute regime, where the motion of a single constituent becomes increasingly confined to a narrow tube. The spatiotemporal dynamics for wave numbers resolving the motion in the confining tube becomes accessible in Brownian dynamics simulations upon employing a geometry-adapted neighbor list. We demonstrate that in such crowded environments the intermediate scattering function, characterizing the motion in space and time, can be predicted quantitatively by simulating a single freely diffusing phantom needle only, yet with very unusual diffusion coefficients.