1H spin diffusion coefficients of highly mobile polymers

Spiegel, Stefan; Schmidt‐Rohr, Klaus; Boeffel, Christine; Spiess, Hans Wolfgang

doi:10.1016/0032-3861(93)90166-8

Cited by 90 publications

(111 citation statements)

References 12 publications

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“…The deviations are within 5%. Moreover, the deviation is quite insensitive to the mixing times, in contrast to earlier observations 17,20 where deviations increase at longer mixing times. The simulated long cubic period was found to be 24.6 nm, also close to the small angle X-ray scattering value of 27.6 nm based on a two-phase model in a body-centered-cubic lattice.…”

Section: B the Interfacial Thicknesscontrasting

confidence: 93%

Spin diffusion and spin-lattice relaxation in multiphase polymers

Wang

Jack

Natansohn

1997

The Journal of Chemical Physics

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Reuse of AIP Publishing content is subject to the terms: https://publishing.aip.org/authors/rights-and-permissions. A model which treats spin diffusion and spin-lattice relaxation in multiphase polymers on the same footing is proposed. This new approach allows for more accurate determination of domain sizes and interfacial thickness in the probed polymers. In a poly͑styrene-b-isoprene͒ copolymer example a significant improvement in the agreement between the NMR measurements and the simulated results can be obtained with the incorporation of a spin-lattice relaxation term into the spin diffusion process. The obtained microphase structural parameters are similar to the small angle X-ray scattering results. In addition, the spin-lattice relaxation times ͑T 1 ) in different domains can be predicted reasonably well based on T 1 s of the component homopolymers and on the microphase structure in the present model.

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Section: B the Interfacial Thicknesscontrasting

confidence: 93%

Spin diffusion and spin-lattice relaxation in multiphase polymers

Wang

Jack

Natansohn

1997

The Journal of Chemical Physics

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“…Mellinger et al (1999) used small-angle X-ray scattering measurements to calibrate the value of the spin diffusion coefficient D. Using this calibration they derived an empirical relationship between T 2 and D (Ds8.2 =10 y6 q(T 2 ) y1.5 q0.007), and calculated a value for the spin diffusion coefficient of water of ;0.001 nm 2 ms y1 when the value of T 2 is of the order of seconds. In contrast, the value obtained for a rigid polymer such as polystyrene is 0.8 nm 2 ms y1 (Spiegel et al 1993). The selfdiffusion (mass transport) coefficient of bulk water is 2=10 9 nm 2 ms y1 at 258C (Cory and Garroway 1990).…”

Section: Resultsmentioning

confidence: 82%

“…The 1 H NMR line widths can be used to estimate the order of magnitude of the spin diffusion coefficient (McBrierty and Packer 1993;Spiegel et al 1993Spiegel et al , 1994. The probability of the dipolar transitions is directly related to the distribution (density) of spins and, importantly, is modulated by molecular motion.…”

Section: Resultsmentioning

confidence: 99%

“…This relationship has been used by Spiegel et al (1993) to estimate the spin diffusion coefficient for polystrene-polybutadiene diblock copolymers. For example, for polystyrene that has a similar line width (40 kHz) to the broad line for a paper sample, they calculated a value of 0.8 nm 2 s y1 .…”

Section: Resultsmentioning

confidence: 99%

“…In solids, the value of D is related to the strength of dipolar couplings, and can be estimated directly from T 2 (Spiegel et al 1993) or by calibration of domain sizes using smallangle X-ray scattering (Mellinger et al 1999). In the more mobile regions of heterogeneous materials, dipolar couplings between nuclei become weaker; however, magnetisation may also be transported spatially by molecular diffusion in combination with dipolar couplings (Fisher et al 1997;Fatkullin et al 1998).…”

Section: Introductionmentioning

confidence: 99%

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The hydration of paper studied with solid-state magnetisation-exchange 1H NMR spectroscopy

et al. 2006

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The wide-line 1 H nuclear magnetic resonance (NMR) spectrum of paper in equilibrium with ambient humidity consists of super-imposed relatively broad and narrow lines. The narrower line is of the order of 2 kHz wide at half the maximum height, while the broader line is of the order of 40 kHz in width at half height. On the basis of these line widths, the narrow line is assigned to water sorbed to the paper, and the broad line to the polymeric constituents of the paper. It was not possible to distinguish between the various polymeric components of paper contributing to the 1 H NMR spectra. A modified Goldman-Shen pulse sequence was used to generate a spatial magnetisation gradient between the polymer and water phases. The exchange of magnetisation between protons associated with water and those associated with the macromolecules in paper was observed. The exchange of magnetisation is discussed within a heat transfer model for homonuclear dipolar coupling, with exchange being characterised by a spin-diffusion coefficient. Consideration of the magnitude of the initial rate of the exchange process and estimates of the spinspin relaxation times based on 1 H line widths indicate that some water must exist in a sufficiently immobile state as to allow homonuclear dipolar interactions between adjacent polymer and water protons. Thus, water sorbed onto paper must exist in at least two states in mass exchange with each other. This observation allows certain conclusions to be drawn about the ratio of free/bound water as a function of moisture content and the dispersal of water within the polymer matrix.

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