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arXiv · 2508.04244

Suspensions of small ultra-soft colloids remain liquids in overcrowded conditions

Nikolaos A. Burger·Alexander V. Petrunin·Ann E. Terry Ralf Schweins·Andrea Scotti
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Abstract

Concentrated suspensions of small ultra-soft colloids (ultra-low crosslinked microgels) are investigated with scattering and steady shear rheology to capture their equilibrium dynamics. The suspensions lack dynamic arrest, although the slow relaxation time $\tau_2$ follows exponential growth with increasing generalized packing fraction, $\zeta$. The zero-shear viscosity grows weakly with $\zeta$, and never diverges in contrast to other soft glass formers, e.g.~star-polymers, microgels, green particles. Their high compressibility allows these ultra-soft spheres to diffuse even in overcrowded environments.

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Nikolaos A. Burger, Alexander V. Petrunin, Ann E. Terry Ralf Schweins, Andrea Scotti. 2025-08-06. Suspensions of small ultra-soft colloids remain liquids in overcrowded conditions. https://arxiv.org/abs/2508.04244

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