Passive polymers in active turbulence undergo a collapse-stretch transition
Abstract
Active processes in living systems generate nonequilibrium forces that deform embedded passive macromolecules. To understand how such dynamics influence polymer conformation, we study a flexible passive chain in an active nematic fluid. Using hybrid simulations, we uncover a length-dependent transition in polymer behavior: long chains align with and stretch along defect-driven flows, while short chains bend and collapse due to localized stresses. These responses are controlled by a competition between the polymer size and the emergent length scale of the active turbulence. Our results reveal a defect-mediated mechanism for conformational control and point toward general physical principles for designing responsive soft materials that couple passive structure to active dynamics.
Cite
@article{arxiv.2509.23382,
title = {Passive polymers in active turbulence undergo a collapse-stretch transition},
author = {Zahra K. Valei and Davide Marenduzzo and Tyler N. Shendruk},
journal= {arXiv preprint arXiv:2509.23382},
year = {2025}
}