Study of rotational mobility of stable nitroxide radicals in solid polymers

Kovarskii, A. L.; Plaček, J.; Sźócs, F.

doi:10.1016/0032-3861(78)90059-9

Cited by 41 publications

(18 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…20 In this context we can conclude that T 0 reflects the effects of both the molar volumes of the probes and their interactions with the polymer. T8 used by Kovarskii et a/., 23 thus, corresponds to T 0 • As shown in Table I, T~ was almost the same for both SPI and SPIii. This fact is reasonably explained, as the moiety rotating around the single bond is the same piperidine ring for both spin probes.…”

Section: Rotational Correlation Timessupporting

confidence: 50%

Effects of Water on the Mobility of Nonionic Spin Probes in Nylon 6 Film

Hamada

Iijima

McGregor

1985

Polym J

View full text Add to dashboard Cite

ABSTRACT:The effects of water on the mobility of nonionic spin probes in nylon 6 film were investigated by electron spin resonance (ESR) measurements. T500, which can be correlated with the glass transition temperature T.. decreased with increasing water content. The rotational correlation time decreased with the rise of the water content at a given temperature, indicating an increase of the mobility of the spin probe. Simultaneously the activation energy for rotation decreased. It was found that the rotation of the spin probe becomes easier as the water content increases.KEY WORDS Spin Probe/ Electron Spin Resonance/ Nylon 6 / Nitroxide / Water / Interaction / Molecular Motion / The effects of water on the physical properties of nylons have been investigated by various methods, e.g., Young's modulus measurement, differential scanning calorimetry, dielectric relaxation measurement and so on. 1 -7 The lowering of the glass transition temperature with an increase of the water content is a general pattern for many polymers, such as poly(ethylene terephthalate) 8 and copoly(tetramethylene terephthalate/ tetramethylene isophthalate ). 9 In order to elucidate quantitatively the effects of water on the mobility of small molecules in solid polymer matrices, the electron spin resonance (ESR) method was used in nylon 6/nitroxide spin probe systems. In reporting data for the spin probe method, T50G which is empirically correlated to the glass transition temperature T/ 0 • 11 has often been used for polymer systems. 12 The rotational correlation times and the activation energies for rotation have also been examined in the same systems. Tormiila et al. investigated the mobility of a spin probe in nylon 6,6 and discussed the effects of water qualitatively. 13 • 14 The effects of water on the characteristics of the polymer/spin probe systems investigated in this work are divided into (1) the effect of water on the mobility of the nylon chain molecule and (2) the effect of water on the microenvironment of the spin probes. The former was estimated in terms of the change of T 50 G and the activation energy for rotation with respect to the water content of nylon 6 film. The latter was discussed in terms of the behavior of probe molecules of three different chemical structures. EXPERIMENTAL SamplesThree spin probes were used. SPI and SPII were prepared as described in our previous paper. 15 SPIii was purchased from Eastman Kodak Co. and used without further purification. Biaxially drawn nylon 6 film (NY-6) 1245

show abstract

Section: Rotational Correlation Timessupporting

confidence: 50%

Effects of Water on the Mobility of Nonionic Spin Probes in Nylon 6 Film

Hamada

Iijima

McGregor

1985

Polym J

View full text Add to dashboard Cite

show abstract

“…1, below 0.25 g water g Ϫ1 dry weight). In these powder spectra the distance between the two outer extrema (2A zz ) is temperature dependent for a number of glass-forming substances at and above their T g (Kumler and Boyer, 1976;Kovarskii et al, 1978;Spielberg and Gelerinter, 1982;Ohta and Kuwata, 1985;Dzuba et al, 1993) (Fig. 1).…”

Section: Epr and St-epr Measurementsmentioning

confidence: 99%

“…From the EPR spectra of the spin probe, R can be assessed (Kumler and Boyer, 1976;Kovarskii et al, 1978;Spielberg and Gelerinter, 1982;Ohta and Kuwata, 1985;Roozen and Hemminga, 1990;Roozen et al, 1991;Dzuba et al, 1993). Whereas R values of 10 Ϫ12 to 10 Ϫ9 s can be calculated from conventional EPR spectra (Knowles et al, 1976), ST-EPR spectroscopy further expands this range to very slow (10 Ϫ6 -10 Ϫ3 s; Hemminga, 1983) and ultra slow (10 Ϫ3 -10 2 s; Van den Dries et al, 1998) molecular motions.…”

mentioning

confidence: 99%

Influence of Water Content and Temperature on Molecular Mobility and Intracellular Glasses in Seeds and Pollen

Buitink

Claessens

Hemminga³

et al. 1998

Plant Physiology

133

152

View full text Add to dashboard Cite

Although the occurrence of intracellular glasses in seeds and pollen has been established, physical properties such as rotational correlation times and viscosity have not been studied extensively. Using electron paramagnetic resonance spectroscopy, we examined changes in the molecular mobility of the hydrophilic nitroxide spin probe 3-carboxy-proxyl during melting of intracellular glasses in axes of pea (Pisum sativum L.) seeds and cattail (Typha latifolia L.) pollen. The rotational correlation time of the spin probe in intracellular glasses of both organisms was approximately 10 ؊3 s. Using the distance between the outer extrema of the electron paramagnetic resonance spectrum (2A zz ) as a measure of molecular mobility, we found a sharp increase in mobility at a definite temperature during heating. This temperature increased with decreasing water content of the samples. Differential scanning calorimetry data on these samples indicated that this sharp increase corresponded to melting of the glassy matrix. Molecular mobility was found to be inversely correlated with storage stability. With decreasing water content, the molecular mobility reached a minimum, and increased again at very low water content. Minimum mobility and maximum storage stability occurred at a similar water content. This correlation suggests that storage stability might be at least partially controlled by molecular mobility. At low temperatures, when storage longevity cannot be determined on a realistic time scale, 2A zz measurements can provide an estimate of the optimum storage conditions.

show abstract

“…3.1, below 0.25 g H 2 0 g dvr 1 ). In such powder spectra, a temperature dependence of the distance between the two outer extrema (2A n ) was observed for a number of glass-forming substances at and above their T g (Kumler and Boyer, 1976; Chapter 3 -Molecular mobility and intracellular glasses Kovarskii et al, 1978;Spielberg and Gelerinter, 1982;Ohta and Kuwata, 1985;Dzuba et al, 1993b) (Fig. 3.1).…”

Section: Section II -Molecular Mobilitymentioning

confidence: 99%

“…From the EPR spectra of the spin probe, the rotational correlation time t R can be assessed (Kumler and Boyer, 1976;Kovarskii et al, 1978;Spielberg and Gelerinter, 1982;Ohta and Kuwata, 1985;Roozen and Hemminga, 1990;Roozen et al, 1991;Dzuba et al, 1993). Whereas x R values can be calculated from conventional EPR spectra in the order of 10~1 2 to 10" 9 s (Knowles et al, 1976), ST-EPR spectroscopy further expands this range to very slow (lO -6 to 10 3 s; Hemminga, 1983) and ultra slow (10~3 to 10 2 s; Van den Dries et al, 1998a) molecular motions.…”

Section: Section II Molecular Mobility Overviewmentioning

confidence: 99%

Biological glasses: nature's way to preserve life

Buitink

2000

Comparative Biochemistry and Physiology Part A: Molecular &

View full text Add to dashboard Cite

Study of rotational mobility of stable nitroxide radicals in solid polymers

Cited by 41 publications

References 7 publications

Effects of Water on the Mobility of Nonionic Spin Probes in Nylon 6 Film

Effects of Water on the Mobility of Nonionic Spin Probes in Nylon 6 Film

Influence of Water Content and Temperature on Molecular Mobility and Intracellular Glasses in Seeds and Pollen

Biological glasses: nature's way to preserve life

Contact Info

Product

Resources

About