Angular dependence of ¹H‐ and ²H‐NMR spectra of H₂O and D₂O absorbed in cellulose acetate film

Abstract

Synopsis ' H -and 'H-NMIt spectra of H,O and D,O ahsorhed in cellulase acetate films were observed while changing the angle between the plane of the film and the magnetic field. 'H-NMII spectra show dipolar splittings that vary depending on the angle. The splitting has a maximum when the surface of t h e film is perpendicular to the magnetic field. From the angular dependence of the dipolar splitting, it is recognized that the proton-proton dipolar axis of water molecules tends to orient perpendicularly to the surface of the film. ' H-NMIt spectra that show quadrupolar splittings also indicate that the quadrupolar axis tends to orient perpendicularly to the film. T h e so-called hound water and free water in the film can exchange rapidly on the NMK time scale, so t h a t the line width and the splitting of the NMII spectra become smaller as the amount of water in t h e film increases. From the temperature dependence of line widths, the apparent reorientational activation energy of water molecules in the film is estimated to be 25 kJ/mol from ' H -N M l t and 31 k,l/mol from 'H-NMII.

Morphological Anisotropy and Proton Conduction in Multiblock Copolyimide Electrolyte Membranes

“…Conductivity, on the other hand, is a macroscopic effect, whereas the length scale probed by 1 H PFG NMR is in the range 100 nm–10 μm, depending on the experimental setup. The orientational anisotropy, describing the degree of alignment of the proton conduction channels, has previously been elucidated by 2 H NMR spectroscopy in a variety of systems. − We note that considerable work related to the combination of 1 H PFG NMR and 2 H NMR has been reported in recent years by Madsen and co-workers. − Using 2 H NMR experiments, we take advantage of the fact that the electric-field gradients of the 2 H nucleus are not completely averaged to zero through the nonisotropic molecular reorientations of the deuterated water molecules (D 2 O). This results in a characteristic 2 H quadrupole splitting that is related to the specific orientational anisotropy.…”

Diffusion and Deuteron Nuclear Magnetic Resonance Study of the Distribution of Water Molecules in Polyimide Films

“…The solubility of NiO in carbonate melts has been reported in several papers (7-13) besides our own (14)(15)(16). The solubility of NiO in carbonate melts has been reported in several papers (7-13) besides our own (14)(15)(16).…”

“…The use of NMR to study water (or other "guest" molecules) that retains some degree of orientation due to anisotropy in the host polymer, i.e., planar structure or welldefined fiber axis, is well documented (10)(11)(12)(13)(14). The nature of the curing process in polyimide films leads to the expectation that structural anisotropies in fully cured films will exist.…”

Deuterium NMR and Water Adsorption Studies of the Effect of Beating on the Water-cellulose Interaction

“…There has been a fair number of studies of cellulose-water interaction by both proton [9][10][11][12] and deuterium NMR [6,[13][14][15][16] These studies have given information on the amount of bound water and the dynamics of the water adsorbed on cellulose fibres .…”