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Ultra-Low-Cross-Linked Microgels Reveal Unexpected Dynamics in Overcrowded Conditions

Burger, Nikolaos A. ; Petrunin, Alexander V. ; Terry, Ann E. LU and Scotti, Andrea LU orcid (2026) In ACS Macro Letters 15(3). p.387-392
Abstract

Ultralow-cross-linked microgels serve as powerful model systems for investigating structure–rheology relationships in soft colloidal suspensions. Using precipitation polymerization, we obtain both self-cross-linked microgels with a weakly cross-linked core, surrounded by an ultrasoft corona (ULC), and regular cross-linked (RC) microgels. ULC microgel suspensions exhibit distinctive rheological responses in crowded conditions. Their linear viscoelastic behavior shares features with critical-like gels, characterized by G′ ∼ G″ ∼ ωn. Large-amplitude-oscillatory-shear measurements reveal a solid–liquid transition reminiscent of polymeric networks lacking a G″ overshoot during yielding. Stress-shear strain rate measurements... (More)

Ultralow-cross-linked microgels serve as powerful model systems for investigating structure–rheology relationships in soft colloidal suspensions. Using precipitation polymerization, we obtain both self-cross-linked microgels with a weakly cross-linked core, surrounded by an ultrasoft corona (ULC), and regular cross-linked (RC) microgels. ULC microgel suspensions exhibit distinctive rheological responses in crowded conditions. Their linear viscoelastic behavior shares features with critical-like gels, characterized by G′ ∼ G″ ∼ ωn. Large-amplitude-oscillatory-shear measurements reveal a solid–liquid transition reminiscent of polymeric networks lacking a G″ overshoot during yielding. Stress-shear strain rate measurements further reveal shear-thinning with a power-law behavior at low shear strain rates, σ ∼ γ̇∼0.25. We attribute this behavior to a fine-tuned balance between polymeric and colloidal contributions. This rheological response to crowding establishes ULC microgels as emergent soft nanocolloids with potential biological relevance, particularly as analogues for the heterogeneity in mechanical softness (compressibility) observed in cell membranes.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
ACS Macro Letters
volume
15
issue
3
pages
6 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • scopus:105033006867
  • pmid:41704194
ISSN
2161-1653
DOI
10.1021/acsmacrolett.5c00787
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2026 The Authors. Published by American Chemical Society
id
6407feff-6969-4999-91dd-609e831358aa
date added to LUP
2026-04-27 16:43:41
date last changed
2026-05-25 18:29:47
@article{6407feff-6969-4999-91dd-609e831358aa,
  abstract     = {{<p>Ultralow-cross-linked microgels serve as powerful model systems for investigating structure–rheology relationships in soft colloidal suspensions. Using precipitation polymerization, we obtain both self-cross-linked microgels with a weakly cross-linked core, surrounded by an ultrasoft corona (ULC), and regular cross-linked (RC) microgels. ULC microgel suspensions exhibit distinctive rheological responses in crowded conditions. Their linear viscoelastic behavior shares features with critical-like gels, characterized by G′ ∼ G″ ∼ ω<sup>n</sup>. Large-amplitude-oscillatory-shear measurements reveal a solid–liquid transition reminiscent of polymeric networks lacking a G″ overshoot during yielding. Stress-shear strain rate measurements further reveal shear-thinning with a power-law behavior at low shear strain rates, σ ∼ γ̇<sup>∼0.25</sup>. We attribute this behavior to a fine-tuned balance between polymeric and colloidal contributions. This rheological response to crowding establishes ULC microgels as emergent soft nanocolloids with potential biological relevance, particularly as analogues for the heterogeneity in mechanical softness (compressibility) observed in cell membranes.</p>}},
  author       = {{Burger, Nikolaos A. and Petrunin, Alexander V. and Terry, Ann E. and Scotti, Andrea}},
  issn         = {{2161-1653}},
  language     = {{eng}},
  month        = {{03}},
  number       = {{3}},
  pages        = {{387--392}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{ACS Macro Letters}},
  title        = {{Ultra-Low-Cross-Linked Microgels Reveal Unexpected Dynamics in Overcrowded Conditions}},
  url          = {{http://dx.doi.org/10.1021/acsmacrolett.5c00787}},
  doi          = {{10.1021/acsmacrolett.5c00787}},
  volume       = {{15}},
  year         = {{2026}},
}