Journal Article

FZJ-2020-01268

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Flow properties reveal the particle-to-polymer transition of ultra-low crosslinked microgels

Scotti, A. (Corresponding author) ; Brugnoni, M.Extern* ; G. Lopez, C. ; Bochenek, S. ; Crassous, J. J. ; Richtering, W. (Corresponding author)Extern*

2020
Royal Soc. of Chemistry London

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Please use a persistent id in citations: doi:10.1039/C9SM01451A

Abstract: Exploiting soft, adaptive microgels as building blocks for soft materials with controlled and predictable viscoelastic properties is of great interest for both industry and fundamental research. Here the flow properties of different poly(N-isopropylacrylamide) (pNIPAM) microgels are compared: regularly crosslinked versus ultra-low crosslinked (ULC) microgels. The latter are the softest microgels that can be produced via precipitation polymerization. The viscosity of ULC microgel suspensions at low concentrations can be described with models typically used for hard spheres and regularly crosslinked microgels. In contrast, at higher concentrations, ULC microgels show a much softer behavior compared to regularly crosslinked microgels. The increase of the storage modulus with concentration discloses that while for regularly crosslinked microgels the flow properties are mainly determined by the more crosslinked core, for ULC microgels the brush-like interaction is dominant at high packing fractions. Both the flow curves and the increase of the storage modulus with concentration indicates that ULC microgels can form glass and even reach an apparent jammed state despite their extreme softness. In contrast, the analysis of oscillatory frequency sweep measurements show that when approaching the glass transition the ultra-low crosslinked microgels behave as the regularly crosslinked microgels. This is consistent with a recent study showing that in this concentration range the equilibrium phase behavior of these ULC microgels is the one expected for regularly crosslinked microgels.

Keyword(s): Polymers, Soft Nano Particles and Proteins (1st) ; Soft Condensed Matter (2nd)

Note: Kein Post-print verfügbar

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Contributing Institute(s):

1. International Helmholtz Research School of Biophysics and Soft Matter (IHRS-BioSoft)
2. Theorie der Weichen Materie und Biophysik (ICS-2)
3. Theoretische Physik der Lebenden Materie (IBI-5)
4. JCNS-FRM-II (JCNS-FRM-II)
5. Heinz Maier-Leibnitz Zentrum (MLZ)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)
2. 6G4 - Jülich Centre for Neutron Research (JCNS) (POF3-623) (POF3-623)
3. 6G15 - FRM II / MLZ (POF3-6G15) (POF3-6G15)
4. IHRS-BioSoft - International Helmholtz Research School of Biophysics and Soft Matter (IHRS-BioSoft-20061101) (IHRS-BioSoft-20061101)

Experiment(s):

1. KWS-2: Small angle scattering diffractometer (NL3ao)

Appears in the scientific report 2020

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Database coverage:
; Allianz-Lizenz / DFG ; Clarivate Analytics Master Journal List ; Current Contents - Physical, Chemical and Earth Sciences ; IF < 5 ; JCR ; National-Konsortium ; Nationallizenz ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Web of Science Core Collection

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