Journal Article

FZJ-2020-01283

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Size effects on rotational particle diffusion in complex fluids as probed by Magnetic Particle Nanorheology

Hess, M.FZJ* ; Roeben, E. ; Rochels, P. ; Zylla, M. ; Webers, S. ; Wende, H. ; Schmidt, A. M. (Corresponding author)Extern*

2019
RSC Publ. Cambridge

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Please use a persistent id in citations: http://hdl.handle.net/2128/24409  doi:10.1039/C9CP04083H

Abstract: Rheological approaches based on micro- or nanoscopic probe objects are of interest due to the low volume requirement, the option of spatially resolved probing, and the minimal-invasive nature often connected to such probes. For the study of microstructured systems or biological environments, such methods show potential for investigating the local, size-dependent diffusivity and particle–matrix interactions. For the latter, the relative length scale of the used probes compared to the size of the structural units of the matrix becomes relevant. In this study, a rotational-dynamic approach based on Magnetic Particle Nanorheology (MPN) is used to extract size- and frequency-dependent nanorheological properties by using an otherwise well-established polymer model system. We use magnetically blocked CoFe2O4 nanoparticles as tracers and systematically vary their hydrodynamic size by coating them with a silica shell. On the polymer side, we employ aqueous solutions of poly(ethylene glycol) (PEG) by varying molar mass M and volume fraction ϕ. The complex Brownian relaxation behavior of the tracer particles in solutions of systematically varied composition is investigated by means of AC susceptometry (ACS), and the results provide access to frequency dependent rheological properties. The size-dependent particle diffusivity is evaluated based on theoretical descriptions and macroscopic measurements. The results allow the classification of the investigated compositions into three regimes, taking into account the probe particle size and the length scales of the polymer solution. While a fuzzy cross-over is indicated between the well-known macroscopic behavior and structurally dominated spectra, where the hydrodynamic radius is equal to the radius of gyration of the polymer (rh ∼ Rg), the frequency-related scaling behavior is dominated by the correlation length ξ respectively by the tube diameter a in entangled solutions for rh < Rg.

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Contributing Institute(s):

1. Theorie der Weichen Materie und Biophysik (ICS-2)
2. International Helmholtz Research School of Biophysics and Soft Matter (IHRS-BioSoft)

Research Program(s):

1. 551 - Functional Macromolecules and Complexes (POF3-551) (POF3-551)
2. IHRS-BioSoft - International Helmholtz Research School of Biophysics and Soft Matter (IHRS-BioSoft-20061101) (IHRS-BioSoft-20061101)

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 ; NCBI Molecular Biology Database ; National-Konsortium ; Nationallizenz ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Web of Science Core Collection

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