25-30 August 2019
Henry Ford Building
Europe/Berlin timezone

Molecular ordering and dynamics in anisotropic soft materials studied by low-resolution proton NMR

30 Aug 2019, 11:30
25m
Lecture Hall D (Henry Ford Building)

Lecture Hall D

Henry Ford Building

Talk Dynamics Dynamics

Speaker

Prof. Kay Saalwächter (Martin-Luther-Univ. Halle-Wittenberg)

Description

With the advent of site-specific isotope labeling and deuteration, the study of local dynamics in biological macromolecules, has reached levels of unprecedented accuracy. There are, however, many cases in e.g. soft materials science, where such strategies are not feasible. While classical carbon-13-based solid-state NMR techniques are often possible, they nevertheless suffer from low sensitivity at natural abundance. Often, proton low-resolution time-domain NMR is fully sufficient, in particular when dealing with materials consisting of identical repeat units. Specifically, multiple-quantum NMR has been established as the most quantitative approach to extract order parameters and correlation times and assess the dynamic heterogeneity in such systems [1]. This is despite of data analyses being restricted to rather simple theories approximating the multi-spin dipolar coupling situation in terms of a second moment. While the methodology can be considered mature for the case of isotropic samples, challenges arise for oriented samples. Here, we highlight a recent methodological advance concerning the order parameter analysis of oriented materials with uniaxial dynamics, tested on liquid crystals [2] and now applied to the investigation of local chain stretching in mechanically deformed swollen elastomers. The latter project extends our earlier work concerned with the molecular-level deformation of polymer chains in bulk elastomers [3].

[1] K. Saalwächter, in: G.A. Webb (ed.), Modern Magnetic Resonance,DOI 10.1007/978-3-319-28275-6_59-2, Springer 2017
[2] A. Naumova, C. Tschierske, K. Saalwächter, Solid State Nucl. Magn. Reson. 2017, 82-83, 22
[3] M. Ott et al., Macromolecules 2014, 47, 7597

Primary authors

Mrs Anna Naumova (Martin-Luther-Univ. Halle-Wittenberg) Prof. Kay Saalwächter (Martin-Luther-Univ. Halle-Wittenberg)

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