Browsing by Subject "Copolymerization"

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    Composition of γ-ray induced triethoxyvinylsilane-methyl methacrylate copolymers determined by XPS
    (Elsevier, 1998) Çaykara, T.; Güven, O.; Süzer, Ş.
    Methyl methacrylate (MMA) was copolymerized with triethoxyvinylsilane (TEVS) using 60Co-γ radiation at varying masses of the liquid monomers in the feed. Their homopolymers PMMA and PTEVS were also prepared by the same method. Thin copolymer and homopolymer blend films were prepared by dissolving the polymers in tetrahydrofuran and casting on clean Teflon or glass substrates. Analysis of the surface composition of these films using XPS indicated that the surfaces of the blend films were completely covered by PTEVS after 10% composition by weight. Similar analysis on the copolymer films, however, revealed that the surfaces of the copolymers contain comparable amounts of PMMA and PTEVS in agreement with the bulk analysis using infrared spectrometry. Hence, use of PMMA/PTEVS copolymers for stone preservation seems feasible by radiation induced polymerization. © 1998 Elsevier Science Ltd. All rights reserved.
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    A conducting composite of polypyrrole II. As a gas sensor
    (Elsevier, 1995) Selampinar, F.; Toppare, L.; Akbulut, U.; Yalçin, T.; Süzer, Ş.
    Pure polypyrrole (PPy) and polypyrrole-polyamide (PPy-PA) composite films were synthesized electrochemically. The gas-sensing ability was investigated for both pure PPy and PPy-PA films. The composite films' response to several gases are better defined and reproducible compared to pristine conducting polymer. Electrochemical behaviour of PPy and PPy-PA electrodes in the presence of pyrrole and pyrrole-free medium is investigated via cyclic voltammetry. Mass spectrometry studies strictly reveal that the composite is completely different to a mechanical mixture. This phenomenon is discussed in comparison to polyaniline-polycarbonate composite. © 1995.
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    Selenium in diketopyrrolopyrrole-based polymers: influence on electronic properties and charge carrier mobilities
    (Wiley-VCH Verlag, 2014) Dhar, J.; Kanimozhi, C.; Yaccobi-Gross, N.; Anthopoulos, T. D.; Salzner, U.; Patil, S.
    Diketopyrrolopyrrole (DPP)-based p-conjugated copolymers with thiophene have exceptionally high electron mobilities. This paper investigates electronic properties and charge carrier mobilities of selenophene containing analogues. Two new copolymers, with alternating thiophene DPP (TDPP) and selenophene DPP (SeDPP) units, were synthesized. Two side-chains, hexyl (Hex) and triethylene glycol (TEG) were employed, yielding polymers designated as PTDPPSeDPP-Hex and PTDPPSeDPP-TEG. Selenophene systems have smaller band gaps, with concomitant enhancement of the stability of the reduced state. For both polymers, ambipolar mobilities were observed in organic fieldeffect transistors (OFET). Grazing incidence X-ray diffraction (GIXD) data indicates preferential edge-on orientation of PTDPPSeDPP-TEG, which leads to superior charge transport properties of the TEG substituted polymer, as compared to its Hex analogue. Time-dependent-density functional theory (TDDFT) calculations corroborate the decrease in the optical band gap with the inclusion of selenophene. Ambipolar charge transport is rationalized by exceptionally wide conduction bands. DSCF calculations confirm the larger electron affinity, and therefore the greater stability, of the reduced form of the selenophene-containing DPP polymer in presence of chloroform.