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Segmental Mean Square Displacement : Field-Cycling ¹H Relaxometry vs Neutron Scattering

Title data

Hofmann, Marius ; Kresse, Benjamin ; Privalov, Alexei F. ; Heymann, Lutz ; Willner, L. ; Aksel, Nuri ; Fatkullin, Nail ; Fujara, F. ; Rössler, Ernst:
Segmental Mean Square Displacement : Field-Cycling ¹H Relaxometry vs Neutron Scattering.
In: Macromolecules. Vol. 49 (2016) Issue 20 . - pp. 7945-7951.
ISSN 1520-5835
DOI: https://doi.org/10.1021/acs.macromol.6b01860

Abstract in another language

Proton (1H) field-cycling (FC) NMR relaxometry is applied to monitor the crossover in the segmental subdiffusion from the Rouse to the constrained Rouse regime in an entangled linear polymer melt. The method probes the dispersion of the spin–lattice relaxation rate R1(ω). Via Fourier transformation the segmental mean square displacement ⟨r2(t)⟩ is calculated from the intermolecular relaxation contribution R1inter(ω) to the total 1H spin–lattice relaxation dispersion R1(ω). As an example we chose poly(ethylene propylene) (M = 200k), and R1inter(ω) is singled out by performing an isotope dilution experiment. The ⟨r2(t)⟩ data obtained by FC NMR is directly compared to such of neutron scattering (NS) available from the literature. Because of different experimental time windows the NS data is converted to a reference temperature assuming frequency–temperature superposition. Absolute agreement is revealed between FC NMR and NS. The data on ⟨r2(t)⟩ confirm the predictions of the tube-reptation model; i.e., the crossover from Rouse regime to constraint Rouse regime is identified, and the tube diameter is estimated to d ≈ (4.6 ± 0.2) nm. Thus, 1H FC NMR has established itself as an alternative route to access subdiffusion.

Further data

Item Type: Article in a journal
Refereed: Yes
Institutions of the University: Faculties
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Former Professors > Professorship Experimental Physics VII - Univ.-Prof. Dr. Ernst Rößler
Faculties > Faculty of Engineering Science
Faculties > Faculty of Engineering Science > Chair Applied Mechanis and Fluid Dynamics
Faculties > Faculty of Engineering Science > Chair Applied Mechanis and Fluid Dynamics > Chair Applied Mechanis and Fluid Dynamics - Univ.-Prof. Dr. Nuri Aksel
Profile Fields
Profile Fields > Advanced Fields
Profile Fields > Advanced Fields > Nonlinear Dynamics
Faculties > Faculty of Mathematics, Physics und Computer Science
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Professorship Experimental Physics VII
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 530 Physics
Date Deposited: 12 Feb 2018 13:34
Last Modified: 13 Feb 2018 07:40
URI: https://eref.uni-bayreuth.de/id/eprint/42256