Researcher:
Gökçümen, Güneş Ekin Atilla

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Undergraduate Student

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Güneş Ekin Atilla

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Gökçümen

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Gökçümen, Güneş Ekin Atilla

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2003 - 20063

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Researcher Of Publications: search.filters.isAuthorOfPublication.b1ec4092-64f6-4e05-bb4e-a3146bf2bac2

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Now showing 1 - 3 of 3
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    Understanding the hydrogen bonding in polyurethanes: quantum mechanical calculations and experimental studies on model systems
    (Amer Chemical Soc, 2003) Department of Chemistry; Department of Chemistry; N/A; Department of Chemistry; Department of Chemistry; Yılgör, İskender; Gökçümen, Güneş Ekin Atilla; Ediz, Volkan; Yılgör, Emel; Yurtsever, İsmail Ersin; Faculty Member; Undergraduate Student; Undergraduate Student; Researcher; Faculty Member; Department of Chemistry; College of Sciences; College of Sciences; N/A; College of Sciences; College of Sciences; 24181; N/A; N/A; N/A; 7129
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    Isopropyl alcohol: an unusual, powerful, 'green' solvent for the preparation of silicone-urea copolymers with high urea contents
    (Elsevier Sci Ltd, 2003) Department of Chemistry; N/A; N/A; N/A; Department of Chemistry; Yılgör, Emel; Gökçümen, Güneş Ekin Atilla; Ekin, Abdullah; Kurt, Pınar; Yılgör, İskender; Researcher; Undergraduate Student; Undergraduate Student; Undergraduate Student; Faculty Member; Department of Chemistry; College of Sciences; College of Sciences; College of Sciences; College of Sciences; College of Sciences; N/A; N/A; N/A; N/A; 24181
    Isopropyl alcohol (IPA) is used as the reaction solvent for the preparation of silicone-urea copolymers. Reactivity of isopropanol with bis(4-isocyanatocyclohexyl)methane (HMDI) was investigated at 23 degreesC using infrared spectroscopy. Spectroscopic studies indicated very low reactivity of IPA towards HMDI at 23 degreesC. High molecular weight segmented silicone-urea copolymers were prepared through the reaction of HMDI with aminopropyl and N-methylaminopropyl terminated polydimethylsiloxane (PDMS) oligomers and three different chain extenders, ethylene diamine (ED), hexamethylene diamine (HMDA) and 2-methyl-1,5-diaminopentane (Dytek A). Number average molecular weights of PDMS oligomers varied between 900 and 7000 g/mol, respectively. Reactions were carried out at room temperature in IPA. Silicone-urea copolymers with urea hard segment content between 10 and 42% by weight were prepared. Thermal and mechanical characterization of the copolymers indicated the formation of microphase-separated systems with excellent tensile strengths. Interestingly, structure of the diamine chain extender did not show any influence on the mechanical properties of the homologous series of silicone-urea copolymers.
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    Anomalous dilute solution properties of segmented polydimethylsiloxane-polyurea copolymers in isopropyl alcohol
    (Elsevier, 2006) Ward, Thomas C.; Department of Chemistry; Department of Chemistry; Department of Chemistry; Yılgör, İskender; Yılgör, Emel; Gökçümen, Güneş Ekin Atilla; Faculty Member; Researcher; Undergraduate Student; Department of Chemistry; College of Sciences; College of Sciences; College of Sciences; 24181; 40527; N/A
    Preliminary characterization of amphiphilic segmented copolymers of polydimethylsiloxane and urea 'hard blocks' was conducted by measuring isopropyl alcohol (primarily) dilute solution viscosities via capillary viscometry. The traditional data analysis techniques, which provide for extrapolation of intrinsic viscosities from these experiments, revealed that increasing concentrations of polymer produced lower reduced viscosities rather than the expected higher values. A very approximate data fit reveals negative Huggins and Kraemer constants from these analyses, which are highly unusual. In a solvent such as DMF, a similar polymer having poly(tetramethylene oxide) and urea blocks and measured with identical conditions exhibited the expected behavior, showing increasing reduced viscosities over concentrations in the same range. However, the non-linearity of the data is suggestive of much more complex hydrodynamic, or supramolecular, interactions that are not clarified by the initial research.