Visualization of residual anisotropic interactions in crosslinked natural rubbers by dipolar local field measurements and 2H natural abundance NMR spectroscopy

Malveau, Cédric; Tékély, Piotr; Canet, Daniel

doi:10.1016/s0926-2040(96)01282-9

Cited by 29 publications

(24 citation statements)

References 20 publications

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“…Model free access is given by the analysis of multiple-quantum built-up [10][11][12][13][14] and decay [15] curves recorded in the initial regime of the excitation/reconversion periods as well as the accordion magic sandwich technique [16]. Chemically site selective residual dipolar couplings can be elucidated by two-dimensional (2D) NMR spectroscopy using, for instance, 13 C-1 H heteronuclear residual dipolar encoded spinning sideband patterns [17], NOESY under magic angle sample spinning (MAS) [18], and DQ MAS NMR spectroscopy [19].…”

Section: Introductionmentioning

confidence: 99%

Enhanced sensitivity to residual dipolar couplings of elastomers by higher-order multiple-quantum NMR

Fechete

Demco

Blümich

2004

Journal of Magnetic Resonance

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Section: Introductionmentioning

confidence: 99%

Enhanced sensitivity to residual dipolar couplings of elastomers by higher-order multiple-quantum NMR

Fechete

Demco

Blümich

2004

Journal of Magnetic Resonance

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“…In the present work, we have recorded the 2 H NMR spectrum for a sample of DBTMB with natural isotopic abundances. As described elsewhere, [49][50][51][52][53][54][55][56][57] given the very low natural abundance of The natural-abundance solid-state 2 H NMR spectrum of DBTMB recorded at ambient temperature (25 °C) with MAS at νr = 2 kHz is shown in Figure 7a. The intensity distribution of the spinning sidebands is very similar to that observed previously in the same type of 2 H NMR measurement at the same MAS frequency for a sample of hexamethylbenzene with natural isotopic abundances.…”

Section: Dynamic Propertiesmentioning

confidence: 98%

Temperature-Dependent Structural Properties, Phase Transition Behavior, and Dynamic Properties of a Benzene Derivative in the Solid State

Zhou

Patterson

Williams

et al. 2019

Crystal Growth & Design

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We report the solid-state structural properties and phase transition behaviour of 1,4-dibromo-2,3,5,6tetramethylbenzene, demonstrating that this material undergoes an order-disorder phase transition below ambient temperature (at ca. 154 K on cooling and ca. 160 K on heating). In both the hightemperature and low-temperature phases, the crystal structure is based on π-stacking of the molecules. In the crystal structure of the high-temperature phase, the bromine occupancy in each substituent site is ca. 1/3 and the methyl group occupancy in each substituent site is ca. 2/3, consistent with statistical orientational disorder of the molecule between six distinct orientations. Natural-abundance solid-state 2 H NMR spectroscopy confirms that, at ambient temperature, this disorder is dynamic via rapid molecular reorientation about an axis perpendicular to the aromatic ring. In the low-temperature phase, the bromine and methyl substituents occupy preferred sites within the crystal structure, with the distribution of site occupancies becoming progressively more ordered on decreasing temperature.

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“…Model free access to RDCs is given by the analysis of multiple-quantum (MQ) build-up [12][13][14][15][16][17][18] and decay [19] curves recorded in the initial regime of the excitation/reconversion periods of the experiment, as well as the accordion magic sandwich technique [20]. Chemically site-selective RDCs can be elucidated by 2D NMR spectroscopy using, for instance, 13 C-1 H heteronuclear residual dipolar couplings and encoded spinning sideband patterns [21]. The NOESY under magic angle sample spinning (MAS) [22] and double-quantum (DQ) MAS NMR spectroscopy are also used [23,24].…”

Section: Introductionmentioning

confidence: 99%

Bimodal 1H Double Quantum Build-Up Curves by Fourier and Laplace-like Transforms on Aged Cross-Linked Natural Rubber

Moldovan

Fechete

2021

Polymers

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The 1H DQ Fourier and Laplace-like spectra for a series of cross-linked natural rubber (NR) samples naturally aged during six years are presented and characterized. The DQ build-up curves of these samples present two peaks which cannot be described by classical functions. The DQ Fourier spectra can be obtained after a numeric procedure which introduces a correction time which depends less on the chosen approximation, spin-½ and isolated CH2 and CH3 functional groups. The DQ Fourier spectra are well described by the distributions of the residual dipolar coupling correlated with the distribution of the end-to-end vector of the polymer network, and with the second and fourth van Vleck moments. The deconvolution of DQ Fourier spectra with a sum of four Gaussian variates show that the center and the width of Gaussian functions increase linearly with the increase in the cross-link density. The Laplace-like spectra for the natural aged NR DQ build-up curves are presented. The centers of four Gaussian distributions obtained via both methods are consistent. The differences between the Fourier and Laplace-like spectra consist mainly of the spectral resolution in the favor of Laplace-like spectra. The last one was used to discuss the effect of natural aging for cross-linked NR.

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Visualization of residual anisotropic interactions in crosslinked natural rubbers by dipolar local field measurements and 2H natural abundance NMR spectroscopy

Cited by 29 publications

References 20 publications

Enhanced sensitivity to residual dipolar couplings of elastomers by higher-order multiple-quantum NMR

Enhanced sensitivity to residual dipolar couplings of elastomers by higher-order multiple-quantum NMR

Temperature-Dependent Structural Properties, Phase Transition Behavior, and Dynamic Properties of a Benzene Derivative in the Solid State

Bimodal 1H Double Quantum Build-Up Curves by Fourier and Laplace-like Transforms on Aged Cross-Linked Natural Rubber

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