Universität zu Köln

Hess, Melissa ORCID: 0000-0002-9255-7185, Roeben, Eric, Rochels, Patricia, Zylla, Markus, Webers, Samira, Wende, Heiko and Schmidt, Annette M. (2019). Size effects on rotational particle diffusion in complex fluids as probed by Magnetic Particle Nanorheology. Phys. Chem. Chem. Phys., 21 (48). S. 26525 - 26540. CAMBRIDGE: ROYAL SOC CHEMISTRY. ISSN 1463-9084

Full text not available from this repository.

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 phi. 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 (r(h) similar to R-g), the frequency-related scaling behavior is dominated by the correlation length xi respectively by the tube diameter a in entangled solutions for r(h) < R-g.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Hess, Melissa UNSPECIFIED orcid.org/0000-0002-9255-7185 UNSPECIFIED Roeben, Eric UNSPECIFIED UNSPECIFIED UNSPECIFIED Rochels, Patricia UNSPECIFIED UNSPECIFIED UNSPECIFIED Zylla, Markus UNSPECIFIED UNSPECIFIED UNSPECIFIED Webers, Samira UNSPECIFIED UNSPECIFIED UNSPECIFIED Wende, Heiko UNSPECIFIED UNSPECIFIED UNSPECIFIED Schmidt, Annette M. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-123851
DOI:	10.1039/c9cp04083h
Journal or Publication Title:	Phys. Chem. Chem. Phys.
Volume:	21
Number:	48
Page Range:	S. 26525 - 26540
Date:	2019
Publisher:	ROYAL SOC CHEMISTRY
Place of Publication:	CAMBRIDGE
ISSN:	1463-9084
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Chemistry > Institute of Physical Chemistry
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language STOKES-EINSTEIN RELATION; NANOPARTICLES; MICRORHEOLOGY; BREAKDOWN; DELIVERY Multiple languages Chemistry, Physical; Physics, Atomic, Molecular & Chemical Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/12385