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Titolo:
Local free volume and structure of polymer gel electrolytes on the basis of alternating copolymers
Autore:
Reiche, A; Dlubek, G; Weinkauf, A; Sandner, B; Fretwell, HM; Alam, AA; Fleischer, G; Rittig, F; Karger, J; Meyer, W;
Indirizzi:
Univ Halle Wittenberg, Inst Tech & Makromol Chem, D-06217 Merseburg, Germany Univ Halle Wittenberg Merseburg Germany D-06217 06217 Merseburg, Germany ITA Inst Innovat Technol GmbH, D-06210 Halle, Germany ITA Inst Innovat Technol GmbH Halle Germany D-06210 06210 Halle, Germany Univ Bristol, HH Wills Phys Lab, Bristol BS8 1TL, Avon, England Univ Bristol Bristol Avon England BS8 1TL Bristol BS8 1TL, Avon, England Univ Leipzig, Fak Phys & Geowissensch, Inst Expt Phys, D-04103 Leipzig, Germany Univ Leipzig Leipzig Germany D-04103 Expt Phys, D-04103 Leipzig, Germany Max Planck Inst Polymerforsch, D-55128 Mainz, Germany Max Planck Inst Polymerforsch Mainz Germany D-55128 55128 Mainz, Germany
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 27, volume: 104, anno: 2000,
pagine: 6397 - 6407
SICI:
1520-6106(20000713)104:27<6397:LFVASO>2.0.ZU;2-M
Fonte:
ISI
Lingua:
ENG
Soggetto:
POSITRON-ANNIHILATION LIFETIME; IONIC-CONDUCTIVITY; TEMPERATURE-DEPENDENCE; DIFFUSION MEASUREMENTS; FIELD GRADIENTS; SELF-DIFFUSION; NMR; SPECTROSCOPY; DIMETHACRYLATE; SPECTRA;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
56
Recensione:
Indirizzi per estratti:
Indirizzo: Reiche, A Univ Halle Wittenberg, Inst Tech & Makromol Chem, Geusaer Str, D-06217 Merseburg, Germany Univ Halle Wittenberg Geusaer Str Merseburg Germany D-06217 any
Citazione:
A. Reiche et al., "Local free volume and structure of polymer gel electrolytes on the basis of alternating copolymers", J PHYS CH B, 104(27), 2000, pp. 6397-6407

Abstract

The relationship between the structure of the polymer and the charge carrier mobility and the ionic conductivity has been studied for a new class of gel electrolytes on the basis of alternating copolymers. These gel electrolytes were prepared by photopolymerization of maleic anhydride and oligo(ethylene glycol)(4) divinyl ether in the presence of various oligo(ethylene glycol), dimethyl ethers with molar masses between 134 and 2000 g/mol, and LiCF3SO3. Thermal properties of the materials were studied by differential scanning calorimetry and dynamic mechanical analysis, which additionally gives structural information. Changes in the free volume as a function of the content of the plasticizer and the salt were studied by positron annihilation lifetime (PAL) spectroscopy. The self-diffusivity of charge carriers and plasticizer in the gel electrolytes was investigated by pulsed field gradient NMR. The ionic conductivity and its pressure dependence were determined by the impedance technique. The gel electrolytes studied are heterogeneous materials composed of a highly crosslinked polymer network (M-c approximateto 600 g/mol) with a T-g approximate to 100 degrees C and of a plasticizer-salt solution with a T-g approximate to -70 degrees C. Hence, two hole size distributions were measured by PAL spectroscopy around 0.26 and 0.34 nm related to the network and the liquid phase, respectively. The activation volume V* calculated from the pressure dependence of the ionic conductivity was V* = 22.7 cm(3)/mol. It is concluded that the charge carrier transport occurs in the liquid phase of the gel electrolytes. However, the network is too dense to provide sufficient distribution and mobility of the plasticizer-salt solution. Self-diffusivity and conductivity of the gel electrolytes studied are not related according to the Nernst-Einstein equation. The ortho-positronium (o-Ps) lifetime tau(3) and its intensity I-3 in the gel were found to be changed if salts were added to the gel. The o-Ps lifetime is discussed in terms of o-Ps bubbles in the plasticizer-salt solution. The o-Psintensity I-3, which decreases with the salt concentration, mirrors inhibition reactions of the o-Ps formation attributed to the anions of the salt.

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Documento generato il 29/03/20 alle ore 01:39:35