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arXiv · 2509.23382

Passive polymers in active turbulence undergo a collapse-stretch transition

Zahra K. Valei·Davide Marenduzzo·Tyler N. Shendruk
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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.

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Zahra K. Valei, Davide Marenduzzo, Tyler N. Shendruk. 2025-09-27. Passive polymers in active turbulence undergo a collapse-stretch transition. https://arxiv.org/abs/2509.23382

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