Radiolysis of Polyethylene Films Containing Arenes:  Bromopyrene Dissociation and Pyrene Binding in Polymer Films

and, Michael Biscoglio; Thomas, J. K.

doi:10.1021/jp9926847

Cited by 13 publications

(9 citation statements)

References 27 publications

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“…Pulse radiolysis studies of polymers containing arene probes have shown a rapid formation of the arene ionic components very shortly after the end of the pulse. 16,17 Therefore, in polyethylene, adding styrene groups in the polymer backbone would lead to charge transfers to the benzene rings, very close to the observation of K. Okamoto 18 during pulse radiolysis study of polystyrene in cyclohexane.…”

Section: Introductionsupporting

confidence: 62%

Aliphatic/Aromatic Systems under Irradiation: Influence of the Irradiation Temperature and of the Molecular Organization

et al. 2013

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With the aim of understanding the electronic excitation, charge or reactive species transfers occurring during irradiation, we studied the role of the aromatic content on ethylene/styrene random copolymers (PES) and on cyclohexane/benzene glasses (amorphous organic solids). Radiation-induced modifications were monitored in situ, at the molecular level, using Fourier transform infrared spectroscopy (FTIR). Irradiations were performed under a vacuum, and thanks to in situ measurements, oxidation was avoided. We followed both the C═C bond creation in the aliphatic moiety and the destruction of the aromatic moiety. The influence of the irradiation temperature was investigated by irradiating samples at room temperature and at 11 K. At such a low temperature, long-range migration hardly occurs and its influence is considerably reduced or could even vanish. Therefore, low temperature irradiation gives insight on the relative influence of reactive species transport and electronic excitation and charge transport. We found that the effect of lowering the PES irradiation temperature from room temperature to 11 K is small, indicating a minor role for the reactive species transport. Moreover, the two chosen systems allow the examination of the relative magnitude of intra- and intermolecular transfers. We demonstrate that, under conditions where reactive species are almost frozen, intermolecular transfers are very efficient.

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Section: Introductionsupporting

confidence: 62%

Aliphatic/Aromatic Systems under Irradiation: Influence of the Irradiation Temperature and of the Molecular Organization

et al. 2013

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“…Diffusion of small molecules has been employed previously to explore the microstructures of several polymer types, 9a, including polyethylenes, 10a-d, but not UHMWPE . To measure in-diffusion rates and calculate the related diffusion constants ( D ), 10a-e,g,h Py - UHMWPE-h ν films were immobilized and immersed in N 2 -saturated 0.95 M DMA /MeOH solutions at constant temperature while the decrease in the intensity of their pyrenyl fluorescence was monitored as a function of time (Table and Figure ).…”

Section: Resultsmentioning

confidence: 99%

“…The microstructure of UHMWPE has been probed by ESR, solid-state 13 C NMR, Raman spectroscopy, and, especially, X-ray diffraction . Others and we have employed photophysical methods to investigate local morphological changes in polymer films, including other types of polyethylene. However, to the best of our knowledge, UHMWPE has not been investigated in this way.…”

Section: Introductionmentioning

confidence: 99%

Structural and Dynamic Investigations of Unstretched and Stretched Ultrahigh Molecular Weight Polyethylene Films. 1-Pyrenyl Attachment by Bombardment with 4.5 MeV Protons and Irradiation with eV Range Photons

et al. 2002

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Several structural and dynamic properties of unstretched and stretched ultrahigh molecular weight polyethylene (UHMWPE) films, as well as UHMWPE films doped with pyrene (Py/UHMWPE) and either irradiated with UV−vis (eV range) photons or bombarded with 4.5 MeV protons, have been investigated. X-ray diffraction patterns of the three-dimensional orthorhombic crystal structure of a uniaxially stretched UHMWPE film, prepared by the gel technique, have been completely indexed for the first time. A minor monoclinic crystalline component, whose importance depends on the draw ratio, is also present. Linear dichroism spectra of dopant pyrene molecules indicate that their long molecular axes are oriented to a smaller extent in highly stretched UHMWPE films than in polyethylene films of much lower crystallinity and draw ratios. When UHMWPE films were stretched, the heat of melting was unchanged, but the melting temperature increased. Stretched films bombarded with 4.5 MeV protons exhibited lower heats of melting and melting temperatures than unstretched bombarded films. When Py/UHMWPE films were bombarded with 4.5 MeV protons or irradiated with >300 nm photons under oxygen-free conditions, 1-pyrenyl groups were attached covalently to polymer chains, yielding Py-UHMWPE. Diffusion of N,N-dimethylaniline (DMA) in to and out of Py-UHMWPE films was followed in real time by fluorescence intensity changes. In unstretched films, at least two parallel diffusion pathways appear to operate. The activation energies for diffusion of DMA in unstretched Py-UHMWPE are larger than those in stretched Py-UHMWPE or in other types of polyethylene films. The results are discussed in terms of the structural differences between unstretched and stretched UHMWPE and other polyethylene types.

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“…Furthermore, the initial deposition of energy by ionizing radiation like X-rays creates local concentrations of high energy (i.e., single ionization spurs) within an alkane medium (Spinks and Woods 1964). Within spurs, processes such as electron ejection leads to hole formation and the generation of stable pyrene radical cations and anions which, upon recombination with electrons, form pyrene excited states (Biscoglio andThomas 2000, Szadkowska-Nicze et al 1992). The predominant processes within the spurs are C-H and C-C bond scissions that lead to the formation of lower molecular weight alkanes (Zagórski 2002) in addition to the attachment processes mentioned here.…”

Section: Resultsmentioning

confidence: 99%

Selectivity and efficiency of pyrene attachment to alkanes induced by broadband X-rays

Brown

Guardala

Price

et al. 2003

An. Acad. Bras. Ciênc.

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Bombardment of pyrene-doped n-heneicosane (C 21 H 44 ) in its orthorhombic solid phase with <1.3> MeV broadband X-rays results in the formation of both mono-and di-heneicosylpyrenes, whereas the same dose in liquid cyclohexane yields only monosubstituted pyrene. In both cases, the reaction efficiency decreases as pyrene concentration is increased from 10 −5 to 10 −2 M. Qualitatively, the overall attachment efficiency is higher in orthorhombic n-heneicosane than in liquid cyclohexane, but the selectivity of attachment is greater in cyclohexane. Differences between these results and those from irradiations of the same samples with eV range photons are discussed.

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Radiolysis of Polyethylene Films Containing Arenes: Bromopyrene Dissociation and Pyrene Binding in Polymer Films

Cited by 13 publications

References 27 publications

Aliphatic/Aromatic Systems under Irradiation: Influence of the Irradiation Temperature and of the Molecular Organization

Aliphatic/Aromatic Systems under Irradiation: Influence of the Irradiation Temperature and of the Molecular Organization

Structural and Dynamic Investigations of Unstretched and Stretched Ultrahigh Molecular Weight Polyethylene Films. 1-Pyrenyl Attachment by Bombardment with 4.5 MeV Protons and Irradiation with eV Range Photons

Selectivity and efficiency of pyrene attachment to alkanes induced by broadband X-rays

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