NMR Relaxation Time Studies of Polystyrene

Froix, Michael F.; Williams, D. J.; Goedde, A. O.

doi:10.1021/ma60050a034

Cited by 29 publications

(15 citation statements)

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“…2 ), with T Ã 2 ¼ 11 μs, consistent with previous measurements in polystyrene [23]. Here, C 0 refers to the value of the correlation function at the start of the first free evolution period, and t refers to the time difference between the end of the Ωðπ/2Þ x pulse and the start of the Ωðπ/2Þ¯x pulse.…”

Section: Magic Echoessupporting

confidence: 82%

High-Resolution Nanoscale Solid-State Nuclear Magnetic Resonance Spectroscopy

et al. 2018

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We present a new method for high-resolution nanoscale magnetic resonance imaging (nano-MRI) that combines the high spin sensitivity of nanowire-based magnetic resonance detection with high-spectralresolution nuclear magnetic resonance (NMR) spectroscopy. Using a new method that incorporates average Hamiltonian theory into optimal control pulse engineering, we demonstrate NMR pulses that achieve high-fidelity quantum control of nuclear spins in nanometer-scale ensembles. We apply this capability to perform dynamical decoupling experiments that achieve a factor of 500 reduction of the proton-spin resonance linewidth in a ð50-nmÞ 3 volume of polystyrene. We make use of the enhanced spin coherence times to perform Fourier-transform imaging of proton spins with a one-dimensional slice thickness below 2 nm.

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Section: Magic Echoessupporting

confidence: 82%

High-Resolution Nanoscale Solid-State Nuclear Magnetic Resonance Spectroscopy

et al. 2018

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“…As already observed by Froix et al, 16 the presence of at least two components can be clearly observed, having respectively TI less than 100 ms and 2' 1 about 1 8, with relative intensities near a 5/3 ratio. This observation clearly supports our previous observation that paramagnetic 02 is selectively adsorbed on the aromatic rings.…”

Section: Resultssupporting

confidence: 81%

Polymorphism in syndiotactic polystyrene: a proton NMR relaxation study

Capitani¹,

Rosa²,

Ferrando³

et al. 1992

Macromolecules

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A marked shortening of T I relaxations in solid aromatic polymers can be attributed to O2 adsorbed on the aromatic rings. This effect, observed as a function of temperature, is modulated by the amount of adsorbed 02, which, in turn, varies according to the molecular packing and crystaUine/amorphous ratio. Within the temperature range 77-400 K, semicrystalline syndiotactic polystyrenes (s-PS) in the a, 8, and y polymorph modifications were studied by pulse lH NMR at 30 MHz. Due to the presence of many relaxation components, 1,2,2-trideuterio-s-PS was synthesized, crystallized, and characterized by X-ray powder diffraction. At low temperature, when both the 0 2 diffusion and the spin-diffusion processes are slow enough, the backbone-deuteriated polymers exhibit multiple T I relaxations: three for a and j3 s-PS and two for y s-PS. These T l components are attributed to crystalline and amorphous phases. From the study of these components as a function of temperature and from direct comparison of TI values in the different phases, the following conclusions were drawn: (i) Clear differentiation was possible between different s-PS polymorphs. (ii) Determination of the crystalline vs amorphous ratio fully consistent with X-ray diffraction data was achieved. (iii) The amorphous component of different semicrystalline s-PS polymorphs could be distinguished.

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“…There are examples given in the literature (Froix, 1984) where the presence of small quantities of LCP blended with a conventional polymer results in mechanical properties significantly better than either component. No explanation for this observation has been advanced.…”

Section: Blends Of Lcp and Conventional Polymersmentioning

confidence: 99%