Browsing by Subject "Condensation reactions"
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Item New Poly(azomethine-urethane)s including melamine derivatives in the main chain: Synthesis and thermal characterization(John Wiley and Sons Inc., 2011) Kaya A.; Yäldäräm M.; Kamacä M.; Avcä A.Up to date, only a few kinds of poly (azomethine-urethane)s (PAMUs) derived from aromatic hydroxy compounds were obtained and studied with thermal degradation steps. Novel PAMUs were prepared using the hydroxy-functionalized Schiff bases derived from melamine and toluene-2,4-diisocyanate. Schiff base prepolymers were synthesized by the condensation reaction of melamine with 4-hydroxybenzaldehyde and 2-hydroxy-1-naphtaldehyde. Characterization was made by UV-Vis, FTIR, NMR, and SEC techniques. Thermal characterizations of the novel PAMUs were carried out by TG-DTA and DSC techniques. Thermal decomposition steps at various temperatures were also clarified and the physical changes of the synthesized PAMUs with exposing to the thermal degradation steps were displayed. © 2011 Wiley Periodicals, Inc.Item Synthesis and thermal characterization of novel poly(azomethine-urethane)s derived from azomethine containing phenol and polyphenol species(2011) Kaya I.; YIldIrIm M.; AvcI A.; KamacI M.Oligophenol-based poly(azomethine-urethane)s (PAMUs) were newly synthesized in two steps. At the first step, the prepolymers including the phenol and oligophenol based-Schiff bases were prepared by a condensation reaction of o-dianisidine with 4-hydroxybenzaldehyde/3-ethoxy-4-hydroxybenzaldehyde, and the polycondensation reactions of the corresponding Schiff bases in an aqueous alkaline media. At the second step, the PAMUs were obtained by copolymerization of the prepolymers with toluene-2,4-diisocyanate (TDI) under an argon atmosphere. The structures of the obtained compounds were confirmed by FTIR, UV-vis, 1H NMR, and 13C NMR, and size exclusion chromatography (SEC) techniques. The synthesized compounds were also characterized by TG-DTA and DSC analyses. Thermal decomposition steps at various temperatures were clarified by FTIR analyses of the degraded products. The physical changes to the synthesized PAMUs after exposing them to the thermal degradation steps are displayed. © 2011 The Polymer Society of Korea and Springer Netherlands.Item Synthesis, characterization, and thermal stability of novel poly(azomethine-urethane)s and polyphenol derivatives derived from 2,4-dihydroxy benzaldehyde and toluene-2,4-diisocyanate(2012) Kaya I.; Avci A.Up to date, only a few kinds of poly(azomethine-urethane)s (PAMUs) were synthesized and studied with thermal degradation steps. However, polyphenol based PAMUs including azomethine linkages have not been investigated yet. The polyurethanes were prepared by condensation reaction of 2,4- dihydroxybenzaldehyde (2,4-DHBA) with toluene-2,4-diisocyanate (TDI) under argon atmosphere. Synthesized polyurethane was converted to its poly(azomethine urethane) species (TP-2AP, TP-3AP, and TP-4AP) by graft copolymerization reactions with amino phenols (2-amino phenol, 3-amino phenol, and 4-amino phenol). Obtained poly(azomethine urethane)s were converted to their polyphenol species (P-TP-2AP, P-TP-3AP, and P-TP-4AP) by oxidative polymerization reaction (OP) using NaOCl as the oxidant. The structures of the obtained compounds were confirmed by FT-IR, UV-vis, 1H NMR, and 13C NMR techniques. The molecular weight distribution parameters of the synthesized compounds were determined by the size exclusion chromatography (SEC). The synthesized compounds were also characterized by solubility tests, TG-DTA, and DSC. Fluorescence measurements were carried out in various concentrated DMF solutions to determine the optimum concentrations to obtain the maximal PL intensities. © 2012 Elsevier B.V.Item Synthesis, characterization, and thermal degradation of new aromatic poly(azomethine-urethane)s and their polyphenol derivatives(Kluwer Academic Publishers, 2012) Kaya I.; Avci A.A new polyurethane was synthesized by condensation reaction of 2,4-dihydroxy benzaldehyde (DHB) with methylene-di-p-phenyl-diisocyanate (MDI) under argon atmosphere. The synthesized polyurethane was converted to its poly (azomethine urethane) species (MP-2AP, MP-3AP, and MP- 4AP) by graft copolymerization reactions with amino phenols (2-amino phenol, 3-amino phenol, and 4-amino phenol). Obtained poly(azomethine urethane)s (PAMUs) were converted to their polyphenol species (P-MP-2AP, P-MP-3AP, and P-MP-4AP) by oxidative polymerization reaction (OP) using NaOCl as the oxidant. The structures of the obtained compounds were confirmed by FT-IR, UV-vis, 1H-NMR, and 13C-NMR techniques. The molecular weight distribution parameters of the synthesized compounds were determined by the size exclusion chromatography (SEC). The synthesized compounds were also characterized by solubility tests, TGDTA, and DSC analyses. Thermal decomposition steps at various temperatures were clarified by FT-IR analyses of degraded products. Fluorescence measurements were carried out in various concentrated DMF solutions to determine the optimum concentrations to obtain the maximal PL intensities. © 2012 Springer Science+Business Media B.V.Item Syntheses and characterization of poly(iminophenol)s derived from 4-bromobenzaldehyde: Thermal, optical, electrochemical and fluorescent properties(Springer Verlag, 2012) Kaya I.; Avci A.; Gültekin O.Schiff base monomers [2-(4-bromobenzylideneamino)phenol and 2-(4-bromobenzylideneamino)-5-methylphenol] were synthesized by the condensation reaction of 4-bromobenzaldehyde with aromatic aminophenols. Then, the monomers were converted to their polyphenol derivatives by oxidative polycondensation reactions (OP) in an aqueous alkaline medium. The structures of the synthesized compounds were characterized by solubility tests, FT-IR, NMR, TG-DTA, DSC and SEC techniques. The HOMO-LUMO energy levels and electrochemical ( E'g ) and optical (Eg) band gaps were calculated from cyclic voltammetry (CV) and UV-Vis measurements, respectively. Cyclic voltammetry (CV) was used to determine the electrochemical oxidation-reduction characteristics. Optical properties were investigated by UV-Vis and fluorescence analyses. Solid state electrical conductivities were measured on polymer films by four point probe technique using a Keithley 2400 electrometer. The effects of electron-donating (?CH3) group at p-position of ?NH2 group in aminophenol on electrochemical and thermal properties were also discussed. Photoluminescence (PL) properties of the synthesized materials were determined in solution forms using different solvents. Fluorescence measurements were carried out in various concentrated solutions to determine the optimum concentrations to obtain the maximal PL intensities. © 2012 Chinese Chemical Society Institute of Chemistry, CAS Springer-Verlag Berlin Heidelberg.Item Synthesis, characterization, optical, and electrochemical properties of thermal stable novel poly(azomethine-ether)s(2014) Kaya I.; Avci A.; Kolcu F.; Çulhaoǧlu S.In this study, the novel Schiff base monomers were synthesized by condensation reactions. Then, these monomers were converted to poly(azomethine-ether)s by oxidative polycondensation (OP) reactions in an aqueous alkaline medium. The structural characterizations of compounds were carried out by FT-IR, NMR, and size exclusion chromatography (SEC). According to the SEC analysis, the calculated number-average molecular weight (M n), weight average molecular weight (Mw), and polydispersity index values of P-2 and P-4 were found to be 17,500 g mol -1, 24,400 g mol-1, and 1.39; and 18,700 g mol -1, 25,600 g mol-1, and 1.36, respectively. The HOMO-LUMO energy levels, electrochemical (), and optical (Eg) band gaps of polymers were calculated from cyclic voltammetry (CV) and UV-vis measurements, respectively. CV was used to determine the electrochemical oxidation-reduction characteristics of polymers. Thermal characterizations of compounds were made by using TG-DTA and DSC techniques. According to TG analysis, polymers with higher initial degradation temperatures (Ton) than those of their monomers indicate that the synthesized polyphenols have higher thermal stabilities than their monomer species. © 2013 Taylor & Francis.Item 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.