Poly(vinyl alcohol) (PVOH) is a water-soluble synthetic polymer, widely used in materials for functional films and moldings, fiber fabric sizing agents, paper coating resins, and adhesives. PVOH is mainly applied in the form of an aqueous solution, yet after its application, insolubility (water resistance) is required. To achieve this, additives are introduced. These additives used with PVOH are cross-linking agents which react with the hydroxyl groups and modified functional groups in PVOH. Because of the poor reactivity of unmodified PVOH, it does not react with cross-linking agents that have functional reactive groups. Therefore, modified PVOH that reacts with a cross-linking agent more successfully is required. These chemical bonding sites are so low in abundance that it is difficult to characterize the cross-linking structure. Solid-state 13C NMR is a powerful technique that can be used for the structural analysis of a polymer material. However, its sensitivity is low, hence it is difficult to determine crosslinking in a polymer, as it makes up only a small proportion of the product. Therefore, solid-state 13C NMR sensitivity can be enhanced by high-field dynamic nuclear polarization (DNP) using strong electron polarization. In this study, the reaction of acetoacetylated PVOH with a cross-linking agent, adipic dihydrazide, was analyzed. This crosslinked PVOH is the most popular vinyl alcohol polymer on the commercial market. The sensitivity enhanced 13C NMR spectra reveal that the carbonyl of the acetoacetyl group of PVOH crosslinks with adipic hydrazide by forming an imine bond (>C?N–) this study also shows that the product has only seven crosslinking sites per molecular chain with a polymerization degree of 1000 and is water resistant.
DNP NMR spectroscopy of cross-linked organic polymers: rational guidelines towards optimal sample preparation #DNPNMR
From The DNP-NMR Blog:
DNP NMR spectroscopy of cross-linked organic polymers: rational guidelines towards optimal sample preparation #DNPNMR
Tanaka, Shinji, Wei-Chih Liao, Atsuko Ogawa, Kazuhiko Sato, and Christophe Copéret. “DNP NMR Spectroscopy of Cross-Linked Organic Polymers: Rational Guidelines towards Optimal Sample Preparation.” Physical Chemistry Chemical Physics 22, no. 6 (2020): 3184–90.
https://doi.org/10.1039/C9CP05208A.
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03-16-2020 04:59 PM
Rapid-melt DNP for multidimensional and heteronuclear high-field NMR experiments #DNPNMR
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Rapid-melt DNP for multidimensional and heteronuclear high-field NMR experiments #DNPNMR
Meerten, S.G.J. van, G.E. Janssen, and A.P.M. Kentgens. “Rapid-Melt DNP for Multidimensional and Heteronuclear High-Field NMR Experiments.” Journal of Magnetic Resonance 310 (January 2020): 106656.
https://doi.org/10.1016/j.jmr.2019.106656.
Verdazyl-ribose: A new radical for solid-state dynamic nuclear polarization at high magnetic field #DNPNMR
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Verdazyl-ribose: A new radical for solid-state dynamic nuclear polarization at high magnetic field #DNPNMR
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Thurber, K.R., et al., Verdazyl-ribose: A new radical for solid-state dynamic nuclear polarization at high magnetic field. J Magn Reson, 2018. 289: p. 122-131.
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05-03-2018 03:56 AM
High-Field Solid-State NMR with Dynamic Nuclear Polarization #DNPNMR
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High-Field Solid-State NMR with Dynamic Nuclear Polarization #DNPNMR
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Lee, D., S. Hediger, and G.D. Paëpe, High-Field Solid-State NMR with Dynamic Nuclear Polarization, in Modern Magnetic Resonance, G.A. Webb, Editor. 2017, Springer International Publishing: Cham. p. 1-17.
https://doi.org/10.1007/978-3-319-28275-6_73-1
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01-08-2018 03:44 PM
Dynamic Polarization and Relaxation of 75As Nuclei in Silicon at High Magnetic Field and Low Temperature #DNPNMR
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Dynamic Polarization and Relaxation of 75As Nuclei in Silicon at High Magnetic Field and Low Temperature #DNPNMR
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Järvinen, J., et al., Dynamic Polarization and Relaxation of 75As Nuclei in Silicon at High Magnetic Field and Low Temperature. Appl. Magn. Reson., 2017. 48(5): p. 473-483.
http://dx.doi.org/10.1007/s00723-017-0875-z
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07-17-2017 04:07 PM
Dynamic Polarization and Relaxation of 75As Nuclei in Silicon at High Magnetic Field and Low Temperature #DNPNMR
From The DNP-NMR Blog:
Dynamic Polarization and Relaxation of 75As Nuclei in Silicon at High Magnetic Field and Low Temperature #DNPNMR
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Järvinen, J., et al., Dynamic Polarization and Relaxation of 75As Nuclei in Silicon at High Magnetic Field and Low Temperature. Appl. Magn. Reson., 2017. 48(5): p. 473-483.
http://dx.doi.org/10.1007/s00723-017-0875-z
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05-02-2017 01:52 AM
[NMR paper] Structural characterization of monellin in the alcohol-denatured state by NMR: eviden
Structural characterization of monellin in the alcohol-denatured state by NMR: evidence for beta-sheet to alpha-helix conversion.
Related Articles Structural characterization of monellin in the alcohol-denatured state by NMR: evidence for beta-sheet to alpha-helix conversion.
Biochemistry. 1993 Feb 16;32(6):1573-82
Authors: Fan P, Bracken C, Baum J
Two-dimensional 1H NMR spectroscopy and hydrogen exchange methods have been used to characterize the alcohol-denatured state of monellin. Monellin is a sweet tasting protein composed of two chains....
Structural analysis of cross-linked poly(vinyl alcohol) using high-field DNP-NMR #DNPNMR
Linear Mode
