Scale-dependent particle diffusivity and apparent viscosity in polymer solutions as probed by dynamic magnetic nanorheology
| Autor: | Hilke Remmer, Micha Gratz, Joachim Landers, Samira Webers, Heiko Wende, Frank Ludwig, Andreas Tschöpe, Dmitry Borin, Annette M. Schmidt, Stefan Odenbach, Melissa Hess |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
chemistry.chemical_classification
Materials science Characteristic length Chemie 02 engineering and technology General Chemistry Polymer Apparent viscosity Physik (inkl. Astronomie) 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics Thermal diffusivity 01 natural sciences 0104 chemical sciences chemistry Chemical physics Mathematik Radius of gyration Particle Particle size 0210 nano-technology Nanoscopic scale |
| Popis: | In several upcoming rheological approaches, including methods of micro- and nanorheology, the measurement geometry is of critical impact on the interpretation of the results. The relative size of the probe objects employed (as compared to the intrinsic length scales of the sample to be investigated) becomes of crucial importance, and there is increasing interest to investigate the dynamic processes and mobility in nanostructured materials. A combination of different rheological approaches based on the rotation of magnetically blocked nanoprobes is used to systematically investigate the size-dependent diffusion behavior in aqueous poly(ethylene glycol) (PEG) solutions with special attention paid to the relation of probe size to characteristic length scales within the polymer solutions. We employ two types of probe particles: nickel rods of hydrodynamic length Lh between 200 nm and 650 nm, and cobalt ferrite spheres with diameter dh between 13 nm and 23 nm, and examine the influence of particle size and shape on the nanorheological information obtained in model polymer solutions based on two related, dynamic-magnetic approaches. The results confirm that as long as the investigated solutions are not entangled, and the particles are much larger than the macromolecular correlation length, a good accordance between macroscopic and nanoscopic results, whereas a strong size-dependent response is observed in cases where the particles are of similar size or smaller than the radius of gyration Rg or the correlation length ξ of the polymer solution. |
| Databáze: | OpenAIRE |
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