Solid Polymers

Scheler, Ulrich

doi:10.1002/9780470999394.ch10

Cited by 2 publications

(4 citation statements)

References 46 publications

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“…1 H magnetizations created by a 90° pulse are spin-locked by a variable rf-pulse block that is 90° out of phase from the initial 90° pulse. An 1 H transverse magnetization that is locked by the spin-lock pulse undergoes signal decay with a relaxation parameter T 1 ρ, which is sensitive over intermolecular or interchain associations via hydrogen bonding or cross-linking. − An indirect CP detection scheme is also required in this case to monitor 1 H magnetizations along the 13 C channel by employing a short 1 H– 13 C CP scheme. Finally, for 13 C T 2 measurements, 13 C echo signals created by a 1 H– 13 C CP scheme are allowed to evolve as a function of variable delay time τ that is placed along both sides of a 180° pulse (Figure D).…”

Section: Methodsmentioning

confidence: 99%

Solid-State NMR Molecular Dynamics Characterization of aHighly Chlorine-Resistant Disulfonated Poly(arylene ether sulfone) Random Copolymer Blended with Poly(ethylene glycol) Oligomers for Reverse Osmosis Applications

Lee¹,

Spano²,

McGrath³

et al. 2011

J. Phys. Chem. B

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We have investigated the dynamics-transport correlations of a chlorine-resistant polymeric system designed as a next-generation reverse osmosis (RO) membrane material by solid-state NMR spectroscopy. A random disulfonated poly(arylene ether sulfone) copolymer in the potassium salt (-SO(3)(-)K(+)) form (BPS-20K) was blended with poly(ethylene glycol)s (PEGs) for improving water permeability. Blended BPS-20K/PEG membranes maintained the intrinsic chlorine-resistant property of BPS-20K, with a somewhat reduced salt rejection. The dynamic characteristics of BPS-20K/PEG blends studied by the spin-lattice relaxation time (T(1)) and rotating frame spin-lattice relaxation time (T(1)ρ) indicated correlations with the observed water uptake and permeability. (1)H T(1) measured on the polymer's aromatic phenylene rings and (1)H T(1)ρ measured on the oxyethylene (-CH(2)CH(2)O-) units of PEG were sensitive to the morphological changes, due to the blending of PEGs, induced in the mixed matrices. Membranes made of BPS-20K/PEG blends, with a lower molecular weight and higher amount of PEGs, that exhibited higher water permeability also provided shorter (1)H T(1) and T(1)ρ relaxation times. PEGs behaved as a plasticizer in the BPS-20K matrix, providing shorter (1)H T(1) times and therefore shorter motional correlation times in the nanosecond regime. (1)H T(1)ρ data have indicated the formation of networks among different polymeric chains via K(+)-oxyethylene ion-dipole interactions. Other properties that exhibit ad hoc correlations with the observed T(1) and T(1)ρ times include density, glass transition temperature, and salt rejection. Additionally, the ring flip motions measured on the hydrophobic phenylene rings did not reveal any correlations to the molecular weight and amount of PEGs blended, suggesting that the blending of PEG molecules modifies only the ionic domains of the BPS-20K polymer matrix.

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Section: Methodsmentioning

confidence: 99%

Solid-State NMR Molecular Dynamics Characterization of aHighly Chlorine-Resistant Disulfonated Poly(arylene ether sulfone) Random Copolymer Blended with Poly(ethylene glycol) Oligomers for Reverse Osmosis Applications

Lee¹,

Spano²,

McGrath³

et al. 2011

J. Phys. Chem. B

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“…For instance, they can be used in a Goldman–Shen55 experiment to utilize spin diffusion in order to obtain information on the size of domains 56. Combination with a wideline separation (WISE) pulse sequence57 enables heteronuclear correlation (two‐dimensional) experiments to be carried out selectively for crystalline and amorphous domains 17…”

Section: Discriminating Experiments In 19f Solid‐state Nmr Spectroscopymentioning

confidence: 99%

“…The first‐reported domain‐selective 19 F‐{ 1 H} experiments on a fluoropolymer (PVDF) involved using a T 1ρ (H) filter (i.e., a spin‐locked delayed‐contact CPMAS pulse sequence) as an introduction to a WISE sequence 17. Such a filter is effective (Figure 9) at ambient probe temperature because T 1ρ (H) for the crystalline domains is significantly longer than for the amorphous domains.…”

Section: Applications To Fluoropolymersmentioning

confidence: 99%

“…6%). However, in the mid‐1990s commercial probes capable of 19 F‐{ 1 H} double resonance, involving high powers in the proton channel but with efficient filtering, became available, so that work in this area began 12–19. There is a residual oddity in that, at relatively low applied magnetic fields, high‐power proton decoupling results in the appearance of the Bloch–Siegert effect,20,21 which causes an apparent chemical shift on 19 F resonances,13,18 as shown in Figure 1 and expressed in Equation (1).…”

Section: Introductionmentioning

confidence: 99%

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Selective NMR Pulse Sequences for the Study of Solid Hydrogen‐Containing Fluoropolymers

Ando

Harris

Hazendonk

et al. 2005

Macromol. Rapid Commun.

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Summary: Fluorine‐19 NMR spectra of solids have some special features, which are discussed in this article. In particular, they generally contain two abundant spin baths (protons and fluorine nuclei). This situation throws up some special operational requirements, as does the study of heterogeneous samples. The relaxation characteristics of heterogeneous systems, which are briefly described herein, frequently permit the use of specific pulse sequences to obtain subspectra for individual components. Various possible selective sequences for use in fluorinated heterogeneous organic solids are listed and their actions rationalized on the basis of molecular mobility. Semicrystalline hydrogen‐containing fluoropolymers form especially suitable systems for such operations, and in order to understand their domain structures it is essential to obtain subspectra of the amorphous and crystalline domains. Examples are given of the use of selective pulse sequences for studying fluoropolymers, especially for poly(vinylidene fluoride) (PVDF) and the copolymer P(VDF75/TrFE25) (TrFE = trifluoroethylene).

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Solid Polymers

Cited by 2 publications

References 46 publications

Solid-State NMR Molecular Dynamics Characterization of aHighly Chlorine-Resistant Disulfonated Poly(arylene ether sulfone) Random Copolymer Blended with Poly(ethylene glycol) Oligomers for Reverse Osmosis Applications

Solid-State NMR Molecular Dynamics Characterization of aHighly Chlorine-Resistant Disulfonated Poly(arylene ether sulfone) Random Copolymer Blended with Poly(ethylene glycol) Oligomers for Reverse Osmosis Applications

Selective NMR Pulse Sequences for the Study of Solid Hydrogen‐Containing Fluoropolymers

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