Spin probe reorientation and its connections with free volume and relaxation dynamics: Diglycidyl-ether of bis-phenol A

Švajdlenková, Helena; Račko, Dušan; Bartoš, Josef

doi:10.1016/j.jnoncrysol.2007.10.028

Cited by 7 publications

(4 citation statements)

References 27 publications

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“…The slow‐rapid crossover change in the spectral parameter of mobility 2 A zz ′ at T 50G = 330 or 333 K in Fig. 3 lies slightly above T

_{italicb 2}^{σ}

= 320 K. Similar coincidences between the characteristic ESR and PALS temperatures have been found in our previous ESR work on a series of spin probes in DGEBA 22…”

Section: Resultssupporting

confidence: 86%

“…Probably, further internal factors of the spin probes, such as their shape, potential interactions with a matrix and especially, the free volume fluctuation due to some specific motion in their surrounding will play some role. Similar geometrical relationships between the have been found in our previous ESR work on a series of spin probes in DGEBA 22. The dynamic aspect of the problem will be discussed in the next part of paper.…”

Section: Resultssupporting

confidence: 75%

“…Similar phenomenological model‐free approach is applied here for analysis of the various parameters describing the spin‐probe dynamics as extracted from their ESR spectra. Very recently, such an approach of comparison of the databases of various methods with respect to the ESR one has been applied in similar combined study of a series of spin probes in smaller molecular glass‐former22 as well as of one spin probe in a simpler polymer 14…”

Section: Introductionmentioning

confidence: 99%

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Spin probe mobility in relation to free volume and relaxation dynamics of glass‐formers: A series of spin probes in poly(isobutylene)

Švajdlenková

Bartoš

2009

J Polym Sci B Polym Phys

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We present the dynamics of a series of three paramagnetic molecules of different volume, mass, and shape in amorphous glass-forming polymer poly(isobutylene) (PIB) as investigated by means of electron spin resonance (ESR) technique. The reorientation behavior of spin probes is related to the ortho-positronium (o-Ps) annihilation in PIB from positron annihilation lifetime spectroscopy (PALS) and the extracted free volume information. It is also related to the dynamic data of PIB from broadband dielectric spectroscopy (BDS), neutron scattering (NS), and nuclear magnetic resonance (NMR) spectroscopy from literature. In the case of the smallest spin probe, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), a discontinuous course of the spectral parameter 2A zz 0 versus T dependence was observed and the subsequent phenomenological model-free analyses of the spectral parameter, 2A zz 0 versus T, as well as of the correlation time, s c , versus 1/T plots provided the characteristic ESR temperatures (T 2Azz X1 , T 50G , T 2Azz X2 ) and (T s X1 , T s c , T s X2 ). These characteristic ESR temperatures were found to be consistent with the characteristic PALS temperatures: T PALS g , T L b1 ¼ T r b1 from temperature dependences of the mean o-Ps lifetime, s 3 , or the width of o-Ps lifetime distribution, r 3 , respectively. In addition, the relationships between the spin probe size, V W Tempo , and the free volume hole size distributions g n (V h ) at the characteristic ESR temperatures indicate the significant influence of the free volume fluctuation at the crossover from slow to rapid regime as well as within the rapid motional regime. On the other hand, the two larger spin probes exhibit a rather continuous 2A zz 0 -T plots with the respective T 50G 's lying in the vicinity of T r b2 independently of their volume, mass and shape, suggesting the common origin of underlying process controlling this T 50G transition. Finally, these mutual PALS and ESR findings were compared with the known dynamic behavior of PIB which suggest that the dynamics of the TEMPO and the larger spin probes are related to free volume fluctuation associated with primary a -and secondary b processes, respectively.

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“…The slow‐rapid crossover change in the spectral parameter of mobility 2 A zz ′ at T 50G = 330 or 333 K in Fig. 3 lies slightly above T

_{italicb 2}^{σ}

= 320 K. Similar coincidences between the characteristic ESR and PALS temperatures have been found in our previous ESR work on a series of spin probes in DGEBA 22…”

Section: Resultssupporting

confidence: 86%

Section: Resultssupporting

confidence: 75%

Section: Introductionmentioning

confidence: 99%

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Spin probe mobility in relation to free volume and relaxation dynamics of glass‐formers: A series of spin probes in poly(isobutylene)

Švajdlenková

Bartoš

2009

J Polym Sci B Polym Phys

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“…A simple method for characterizing the nitroxide probe dynamics is to plot the extreme separation of the EPR outer lines (2 A′ zz parameter) as a function of temperature (Figure ). In our wet hydrogel, the behavior of 2 A′ zz is similar to that observed in a large number of synthetic polymers and low-molecular weight glass-formers. − Usually a characteristic temperature T 50G is identified, which corresponds to the temperature at which 2 A′ zz = 50 Gauss. If the probe size matches a characteristic length of the glass-forming matrix, the temperature T 50G corresponds to a “high frequency” glass transition temperature since it corresponds to the temperature at which the relaxation time crosses the window of ∼10 −8 s; such a temperature is generally expected to be higher than, but correlated with, T g (the calorimetric glass transition temperature).…”

Section: Resultssupporting

confidence: 72%

Solvation of a Probe Molecule by Fluid Supercooled Water in a Hydrogel at 200 K

et al. 2008

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By combining electron paramagnetic resonance (EPR) measurements on a nitroxide probe and differential scanning calorimetry (DSC), we demonstrate existence of liquid supercooled water in a silica hydrogel with high hydration level down to temperatures of at least 198 K. Besides the major fraction of liquid supercooled water, a minor fraction crystallizes at about 236 K during cooling and melts at 246 K during heating. The liquid domains are of sufficient size to solvate the nearly spherical paramagnetic probe molecule TEMPO with a diameter of about 6 A. Analysis of EPR spectra provides the rotational correlation time of the probe that is further used to compare the viscosity of the supercooled water with the one of bulk water. In the temperature interval investigated, the supercooled water behaves as a fragile liquid and eventually solidifies at 120 K to a glass that incorporates the probe molecules.

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On the relationships between guest molecular dynamics and free volume in a series of small molecular and polymer glass-formers

Švajdlenková

Šauša

Iskrová-Miklošovičová

et al. 2012

Chemical Physics Letters

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Spin probe reorientation and its connections with free volume and relaxation dynamics: Diglycidyl-ether of bis-phenol A

Cited by 7 publications

References 27 publications

Spin probe mobility in relation to free volume and relaxation dynamics of glass‐formers: A series of spin probes in poly(isobutylene)

Spin probe mobility in relation to free volume and relaxation dynamics of glass‐formers: A series of spin probes in poly(isobutylene)

Solvation of a Probe Molecule by Fluid Supercooled Water in a Hydrogel at 200 K

On the relationships between guest molecular dynamics and free volume in a series of small molecular and polymer glass-formers

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