Browsing by Subject "Polyurethane prepolymers"

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    The crosslinked poly(azomethine-urethane)s containing o-hydroxyazomethine: Tunable multicolor emission, photophysical and thermal properties
    (Elsevier B.V., 2015) Kamaci M.; AvcI A.; Kaya I.
    This article presents synthesis, photophysical, electrochemical, thermal, and morphological properties of the crosslinked polyurethanes (CLPUs). CLPUs were synthesized in two main steps. In the first step, aldehyde functionalized polyurethane prepolymer was synthesized using 2,4-dihydroxy benzaldehyde and hexamethylene diisocyanates. In the second step, the prepared prepolymer was converted to the crosslinked polyurethane derivatives using different diamines via condensation reaction. Diamines with various chain length and side-group substitutions were used as crosslinker. Photophysical properties of the crosslinked polyurethanes were investigated using UV-vis and photoluminescence (PL) spectra techniques. Fluorescence measurements showed that CLPUs exhibited multicolor emission behavior. Additionally, a linear relationship is determined between the excitation energies and the obtained emission maxima and, this property allows tuning the PL color by changing the source light energy on the desired scale. © 2015 Elsevier B.V. All rights reserved.
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    Synthesis of Novel crosslinked Poly(azomethine-urethane)s: Photophysical and thermal properties
    (Elsevier Ltd, 2015) Avci A.; Kamaci M.; Kaya I.; Yildirim M.
    This paper describes synthesis, photophysical, electrochemical and thermal properties of some new flexible crosslinked poly(azomethine-urethane)s. Synthesis procedure includes two main steps: The first one is the synthesis of a polyurethane prepolymer (TP) using toluene-2,4-diisocyanate and 2,4-dihydroxy benzaldehyde, and the second step is the synthesis of resulting flexible crosslinked poly(azomethine-urethane) derivatives by conventional polycondensation reaction of TP with different aliphatic diamines. Diamines with various chain lengths (6-12 methylene numbers) were used to obtain various resulting polymers with different physical properties. Photophysical properties of the flexible crosslinked poly(azomethine-urethane)s were investigated using photoluminescence (PL). PL results showed that the flexible crosslinked poly(azomethine-urethane)s exhibited multicolor emission behavior. A linear relationship was observed between the excitation energies and the obtained emission maxima. This characteristic enabled adjusting the PL color at the desired scale. Thermal and morphological properties of the polymers were also investigated using TG-DTA, DSC and AFM techniques. © 2015 Elsevier B.V. All rights reserved.