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    Öğe
    Poly(styrene-b-tetrahydrofuran)/Clay Nanocomposites by Mechanistic Transformation
    (Wiley, 2009) Yenice, Zuleyha; Tasdelen, M. Atilla; Oral, Ayhan; Guler, Cetin; Yagci, Yusuf
    Synthesis of poly(styrene-block-tetrahydrofuran) (PSt-b-PTHF) block copolymer on the surfaces of intercalated and exfoliated silicate (clay) layers by mechanistic transformation was described. First, the polystyrene/montmorillonite (Pst/MMT) nanocomposite was synthesized by in situ atom transfer radical polymerization (ATRP) from initiator moieties immobilized within the silicate galleries of the clay particles. Transmission electron microscopy (TEM) analysis showed the existence of both intercalated and exfoliated structures in the nanocomposite. Then, the PSt-b-PTHF/MMT nanocomposite was prepared by mechanistic transformation from ATRP to cationic ring opening polymerization (CROP). The TGA thermogram of the PSt-b-PTHF/MMT nanocomposite has two decomposition stages corresponding to PTHF and PSt segments. All nanocomposites exhibit enhanced thermal stabilities compared with the virgin polymer segments. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2190-2197, 2009
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    Öğe
    Ring-opening metathesis polymerization of bicyclo[2.2.1]hepta-2,5-diene (norbornadiene) initiated by new ruthenium(II) complex
    (Wiley-Blackwell, 2013) Yalcinkaya, Esra Evrim; Dayan, Osman; Balcan, Mehmet; Guler, Cetin
    The polymerization of norbornadiene (NBD) initiated by a novel ruthenium (Ru)(II) complex (3) containing 1,1'-pyridine-2,6-diylbis[3-(dimethylamino)prop-2-en-1-one] (1) as ligand has been investigated. Ru complexes exhibit more catalytic activity in the ring-opening metathesis polymerization (ROMP) of NBD when activated with trimethylsilyldiazomethane (TMSD). The influence of the various experimental parameters such as reaction time and temperature, nature of the solvent and catalyst, ratio of the NBD/Ru, and TMSD addition has been investigated. The polymers have been obtained in high yields with a relatively low polydispersity index for ROMP and a high (M) over bar (n) and (M) over bar (w) values in a monomodal distribution. Their structures have been determined by means of FTIR and H-1-NMR spectroscopy. Thermal properties have been determined via thermogravimetric analysis and DTG methods. The NBD polymerization results that initiated by Ru-based catalyst coordinated to amine ligand have been compared to initiated by [RuCl2(p-cymene)](2). (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 127: 1691-1696, 2013
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    Öğe
    Synthesis of poly-2-hydroxyethyl methacrylate-montmorillonite nanocomposite via in situ atom transfer radical polymerization
    (Cambridge Univ Press, 2008) Oral, Ayhan; Shahwan, Talal; Guler, Cetin
    The poly-2-hyroxyethyl methacrylate (PHEMA)/clay nanocomposite was synthesized by in Situ atom transfer radical polymerization (ATRP) from initiator moieties immobilized within the silicate galleries of the clay particles. To produce organically modified montmorillonite (MMT) that has ATRP initiator moiety, a new catalyst that consists of quaternary ammonium salt moiety and an initiator moiety was synthesized. This initiator was intercalated into the interlayer spacing of the MMT. The polymerization reaction was carried Out in a mixed solvent system consisting of methyl ethyl ketone and 1-propanol at 50 degrees C, using the initiator that has been already synthesized with a copper bromide catalyst. The 2, 2'-bipyridyl (bpy) complex was used as ligand. The products were characterized via Fourier transform infrared, nuclear magnetic resonance (H-1 NMR, C-12 NMR), transmission electron microscopy, x-ray diffraction. thermogravimetric analysis, and differential scanning calorimetry.