Poly(vinyl acetate) dynamics studied by proton and carbon-13 nuclear magnetic resonance in the solid state

Ganapathy, Swapna; Chacko, V. P.; Bryant, R. G.

doi:10.1021/ma00158a015

Cited by 22 publications

(16 citation statements)

References 17 publications

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“…We note that the reason it is possible to measure the rates as high as we have at low fields is because the relaxation rates at high field are low, and switching the field to a proton Larmor frequency of 21 MHz, where we measure the magnetization, quenches relaxation and preserves intensity. The NMR relaxation profile for the dry tissue is similar to that reported for lyophilized protein samples and polymers (59,60). The details of the relaxation in the dry tissue may be of interest for fundamental reasons but represent a difficult system to model.…”

Section: Resultsmentioning

confidence: 99%

The magnetic field dependence of proton spin relaxation in tissues

Bryant

Mendelson

Lester

1991

Magnetic Resonance in Med

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The magnetic field dependence of water-proton relaxation is reported for a simple protein solution, a cross-linked protein solution, and a series of rat tissues, fresh, dried and rehydrated. The shape of the magnetic field dependence associated with water proton relaxation in tissues is accounted for by magnetic dipole-dipole interactions between the mobile water spins and the immobile spin populations of the nonrotating components of the tissue coupling the behavior of the immobilized spin system to that of the mobile water spin system. The effect of this coupling is to impart the field dependence of the relaxation associated with the immobilized spin population to that of the mobile water spins that are observed in most relaxation and imaging experiments.

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Section: Resultsmentioning

confidence: 99%

The magnetic field dependence of proton spin relaxation in tissues

Bryant

Mendelson

Lester

1991

Magnetic Resonance in Med

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“…It is known that the T g s are good indicators and reflect the plasticization process. Hence, the effect of plasticizer can easily be observed through the T g s. The reduction in T g of thin polymeric films such as PVAc, poly(styrene), and poly(methyl methacrylate) due to the presence of diluents such as water or plasticizers has been reported. ,,− The effect of plasticizer on T g reduction has also been found in supported PMMA films on silica . However, many of these studies have focused on films of thicknesses much greater than than the amounts reported herelittle or no work on such small adsorbed amounts around a nanometer or so.…”

Section: Discussionmentioning

confidence: 99%

Does Plasticizer Penetrate Tightly Bound Polymer in Adsorbed Poly(vinyl acetate) on Silica?

Hetayothin

Cabaniss²,

Blum

2017

Macromolecules

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When only tightly bound poly(vinyl acetate) (PVAc) was adsorbed on silica, the plasticizer, di(propylene glycol) dibenzoate (DPGDB), was not effective in lowering its glass transition. To determine why the plasticizer was not effective, we probed the behavior of the deuterated plasticizer di(propylene glycol) dibenzoate (DPGDB-d 10)/PVAc/silica system using deuterium (2H) solid state NMR and temperature-modulated differential scanning calorimetry (TMDSC). PVAc with 37% (w/w) of plasticizer/polymer was adsorbed on silica in adsorbed amounts of 2.60 and 0.76 mg PVAc/m2 silica. The dynamics of the plasticizer in the adsorbed PVAc was found to be more motionally heterogeneous than that observed in bulk samples. The NMR results provided firm evidence that when there is only a small amount of adsorbed polymer (e.g., only tightly bound polymer at less than 0.8 mg/m2), the plasticizer was effectively excluded from the polymer chains at the silica–polymer–air interface. When excluded from the tightly bound polymer, the plasticizer existed in an environment that was similar to that of pure plasticizer. At larger adsorbed amounts, the plasticizer was effective at lowering the T g of the adsorbed polymer.

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“…It is very clear that the present data do not fit the Lorentzian functions usually found for liquid samples (26). However, it is possible to generate relaxation profiles similar to those observed by modeling a distribution of interaction strengths or correlation times (27). Kimmich and Winter have proposed a model based on fluctuations of the protein backbone (21).…”

Section: Shape Of the Relaxation Projlementioning

confidence: 99%

Water–proton nuclear magnetic relaxation in heterogeneous systems: Hydrated lysozyme results

Lester

Bryant

1991

Magnetic Resonance in Med

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Spin-lattice relaxation rates of water protons in hydrated immobilized lysozyme are measured as a function of magnetic field strength. The dependence of water relaxation versus hydration is presented from 35 to 55% by weight water content. The water-proton relaxation is directly coupled to that of the protein and the coupling exists in the absence of chemical exchange. A model is applied where relaxation within the two proton phases is coupled through a dipolar cross-relaxation mechanism as well as chemical exchange. The observed amplitudes of the water-proton relaxation profiles scale with the ratio of protein to water protons as well as the protein-proton relaxation rate. The field dependence of the protein-proton spin-lattice relaxation is presented in the presence of D2O where a cross-relaxation coupling is absent. The coupled relaxation model accounts well for the NMR relaxation data as a function of magnetic field strength which is similar to measurements on other heterogeneous systems such as tissues.

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Poly(vinyl acetate) dynamics studied by proton and carbon-13 nuclear magnetic resonance in the solid state

Cited by 22 publications

References 17 publications

The magnetic field dependence of proton spin relaxation in tissues

The magnetic field dependence of proton spin relaxation in tissues

Does Plasticizer Penetrate Tightly Bound Polymer in Adsorbed Poly(vinyl acetate) on Silica?

Water–proton nuclear magnetic relaxation in heterogeneous systems: Hydrated lysozyme results

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