Photochemistry of Ketone Polymers. XI. Phosphorescence as a Probe of Subgroup Motion in Polymers at Low Temperatures

Somersall, A. C.; Dan, E.; Guillet, J. E.

doi:10.1021/ma60038a016

Cited by 105 publications

(84 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Specifically, over limited temperature ranges, the diffusion coefficient D behaves according to eq. [3] (2,3,8,9,15,20), which is analogous to the Arrhenius equation. The exponential term thus represents the fraction of diffusing molecules able to surmount a diffusion activation barrier EaCt at the temperature T. The magnitude of this exponential term ranges from 1.0 at large T to 0 at low T. The activation barrier E,,, is believed to derive principally from characteristic motions of the macromolecule in a given temperature domain, …”

Section: Effect Of Temperature On Dmentioning

confidence: 96%

“…Over comparatively large temperature ranges, the diffusion coefficient behaved according to eq. [3], and we were able to obtain values of E,,, and Do for films under a number of different conditions.…”

mentioning

confidence: 99%

“…For those interested in polymer photophysics and photochemistry, such studies are useful because oxygen is an efficient quencher of excited electronic states (1)(2)(3)(4)(5)(6). Studies of oxygen diffusion should also be useful for those interested in packaging materials, protective coatings, polymer oxidative degradation, and membranes for gas separation.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Activation barriers for oxygen diffusion in polystyrene and polycarbonate glasses: effects of codissolved argon, helium, and nitrogen

Wang¹,

Ogilby²

1995

Can. J. Chem.

View full text Add to dashboard Cite

A recently developed spectroscopic technique was used to determine oxygen diffusion coefficients as a function of temperature for polystyrene and polycarbonate films. Data were recorded at total pressures <300 Torr over the temperature range 5–45 °C under conditions in which argon, helium, and nitrogen, respectively, were copenetrants. In all cases, the presence of the additional gas caused an increase in the oxygen diffusion coefficient. Arrhenius plots of the data yield (a) a diffusion activation barrier, Eact, and (b) a diffusion coefficient, D0, that represents the condition of "barrier-free" gas transport for the temperature domain over which the Arrhenius plot is linear. For all cases examined in both polystyrene and polycarbonate, D0 increased with an increase in the partial pressure of added gas. In polystyrene, the presence of an additional gas did not change Eact. In polycarbonate, Eact obtained in the presence of helium and argon likewise did not differ from that obtained in the absence of the copenetrant. When nitrogen was the added gas, however, a larger value of Eact was obtained. This latter observation is interpreted to reflect the plasticization of polycarbonate by nitrogen. Eact and D0 data are discussed within the context of a model that distinguishes between dynamic and static elements of free volume in the polymer matrix. Keywords: oxygen diffusion, polystyrene, polycarbonate, activation barrier.

show abstract

Section: Effect Of Temperature On Dmentioning

confidence: 96%

mentioning

confidence: 99%

See 1 more Smart Citation

Activation barriers for oxygen diffusion in polystyrene and polycarbonate glasses: effects of codissolved argon, helium, and nitrogen

Wang¹,

Ogilby²

1995

Can. J. Chem.

View full text Add to dashboard Cite

show abstract

“…These values can be compared with the classically measured (15) value of 1.9 x 10-13. Guillet (2,3,7,8) and co-workers and MacCallum and Rudkin (17) extended this kind of analysis to transient measurements on thin polymer films. In these experiments, they measured the rate of decrease of luminescence intensity from the dyedoped film following exposure of the film to oxygen.…”

Section: Previous Analyses Of Oxygen Quenching In Thin Filmsmentioning

confidence: 99%

“…The Guillet group was one of the first to report experiments involving oxygen diffusion into dye-doped polymer films (7,8). They calculated diffusion coefficients from their data, but in their data analysis they made simplifying assumptions about the connection between the oxygen diffusion and the extent of luminescence quenching in the film.…”

mentioning

confidence: 99%

Luminescence measurements of oxygen permeation and oxygen diffusion in thin polymer films

Yekta¹,

Masoumi²,

Winnik³

1995

Can. J. Chem.

View full text Add to dashboard Cite

Abstract:A new method is developed for analyzing the diffusion of oxygen in thin polymer films via fluorescence quenching measurements. We begin by reviewing previous methods, all of which involve approximations, for the measurement of permeability and diffusion coefficient by luminescence quenching; their shortcomings are clarified. An exact analytic theory is developed that successfully couples Fick's laws of diffusion to the Stern-Volmer equation of intensity quenching. Various modes of experimentation with polymeric films are considered. The equations we derive make the unexpected prediction that the rate of emission intensity decay when O2 diffuses into a polymer film is much faster than the rate of emission intensity enhancement when O2 diffuses out of the same film, even when the molecular diffusivity remains unchanged. Experiments show that this is indeed the observed behaviour.Key words: diffusion coefficient, oxygen permeability, polymers, quenching, luminescence quenching, Fick's laws, Stern-Volmer equation.RCsumC : Faisant appel h des mesures de dtcroissance de la fluorescence, on a mis au point une nouvelle mtthode pour analyser la diffusion de I'oxygkne dans des films minces de polymkre. On passe en revue les mtthodes dtcrites anttrieurement pour la mesure de la permtabilitt et du coefficient de diffusion par dtcroissance de la luminescence; toutes ces mtthodes impliquent des approximations et on a clarifit leurs limitations. On a mis au point une thtorie analytique exacte qui relie avec succks les loisde diffusion de Fick avec l'tquation de Stern-Volmer de la dtcroissance de l'intensitt. On considkre divers modes d'exptrimentation avec des films polymtriques. Les tquations que l'on a dtrivtes permettent de faire la prtdiction inattendue que la vitesse de dtcroissance de l'intensitt de l'tmission, lorsque du O2 diffuse dans un film de polymkre, est beaucoup plus rapide que la vitesse d'augmentation de l'intensitt de l'tmission lorsque le O2 diffuse du m&me film, m&me lorsque la diffusivitt moltculaire demeure la m&me. Les exptriences montrent que le comportement observt correspond A cette prtdiction. Mots clCs : coefficient de diffusion, permtabilitt A l'oxygkne, polymkres, dtcroissance, dtcroissance de la luminescence, lois de Fick, Cquation de Stern-Volmer.[Traduit par la rtduction] value, and at steady state, the flux measures the permeability Oxygen diffusivity in polymers is most commonly determined by measuring the rate of oxygen permeation across a membrane. One exposes one side of the polymer film to oxygen at time zero and measures the flux of oxygen across the film as a function of time. Knowing the dimensions of the film and the partial pressure of oxygen on the high-pressure side, one can calculate the diffusion coefficient and the permeability from the flux (1). The diffusion coefficient Do, is determined from the kinetics of the approach of the 0, flux to its steady-state

show abstract

Luminescence studies of polymer matrices. III. Characterization and evaluation of acrylic acid-based polymers as hosts for a phosphorescent coding system

Ebdon

Soutar

Brown³

et al. 1999

J. Polym. Sci. B Polym. Phys.

View full text Add to dashboard Cite

Photochemistry of Ketone Polymers. XI. Phosphorescence as a Probe of Subgroup Motion in Polymers at Low Temperatures

Cited by 105 publications

References 8 publications

Activation barriers for oxygen diffusion in polystyrene and polycarbonate glasses: effects of codissolved argon, helium, and nitrogen

Activation barriers for oxygen diffusion in polystyrene and polycarbonate glasses: effects of codissolved argon, helium, and nitrogen

Luminescence measurements of oxygen permeation and oxygen diffusion in thin polymer films

Luminescence studies of polymer matrices. III. Characterization and evaluation of acrylic acid-based polymers as hosts for a phosphorescent coding system

Contact Info

Product

Resources

About