Diffusion studies in confined nematic liquid crystals by MAS PFG NMR

Kinetics of the grating formation in holographic polymer-dispersed liquid crystals: NMR measurement of diffusion coefficients

“…The diffusion coefficient for pure E7 (100 %) was obtained using MAS, while all other values were obtained from static measurements coefficient of pure E7, which is in the nematic state, is higher than what might be expected from extrapolating the diffusion coefficients of the isotropic mixtures. This observation is in agreement with temperature-dependent measurements on 5CB by NMR diffusometry under MAS, which exhibit a similar increase of D upon transition from the isotropic to the nematic phase [13]. Since diffusion in a nematic sample is anisotropic (D || >D ┴ ) [15], the observed high value may indicate a preferred director orientation along the axis of sample rotation.…”

“…2b) [12] or sine-shaped gradients (Fig. 2c) [13] were used for the static and MAS experiments, respectively.…”

HR-MAS NMR Spectroscopy in Material Science

“…[50] Surprisingly, only a single 1 H HR-MAS NMR diffusion study of a non-biological LC material confined in nanopores has been reported. [51] …”

“…By utilizing PFG techniques it was possible to measure the diffusion constants as a function of temperature through the isotropization temperature of the liquid crystal, thus demonstrating that for this case there is only a minor reduction in the diffusion rates with molecular confinement. [51] …”

1H NMR Investigations of Activated Carbon Loaded with Volatile Organic Compounds: Quantification, Mechanisms, and Diffusivity Determination

“…Such a signal can be generated by a part of the adsorbed molecules exhibiting large dipolar coupling 31,32 . For this specific purpose, high field 1 H NMR recordings correlated with very high MAS frequencies were carried out with the aim of detecting such interaction effects.…”