Kevser Temizkan

Regioselective synthesis of polygamma (γ) acid

The oxidative polymerization of 6-amino-4-hydroxy-2-naphthalenesulfonic acid in an aqueous alkaline medium leads to the formation of a polygamma (γ) acid consisting of regioselective 1–4 oxazine rings. Spectral characterizations were performed by NMR, FT-IR, and UV-Vis techniques. The average molecular weight and polydispersity index of the gamma acid polymer (γ-AP) were found to be 32 000 Da and 1.42, respectively. γ-AP also presented an uncommon multicolored emission behavior in dimethylsulfoxide (DMSO). When excited at 405, 480, and 532 nm, γ-AP emitted blue, green and yellow light, respectively. X-ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic mechanical analyses (DMA), and transmission electron microscopy (TEM) illustrated that γ-AP is composed of semicrystalline nanofiber structures with different lengths between 10–500 nm. The kinetic parameters related to the solid state thermal decomposition of γ-AP were determined using differential isoconversional methods (Friedman and Kissenger) and integral isoconversional methods (FWO, KAS, Tang, Starink and Bosewell). By using the Tang, KAS, FWO, Starink, Bosewell, Kissenger and Friedman methods, the average values of the activation energies were calculated to be 184.4, 184.4, 185.4, 188.5, 183.6, 179.7 and 187.1 kJ mol−1, respectively. The master plot curves also suggested a diffusion-type kinetic model for the solid state thermal decomposition stage of γ-AP.

Synthesis of thermally stable and low band gap poly(azomethine-urethane)s containing fluorene unit in the backbone

New poly(azomethine-urethane)s (PAMU)s were prepared to investigate the effects of different four diisocyanates on some physical properties such as thermal stability, optical and electrochemical properties. First, the fluorene Schiff base was synthesized as in the literature. Then, this Schiff base was converted to poly(azomethine-urethane)s using diisocyanates (2,4-toluenediisocyanate, 1,4-phenylene diisocyanate, methylene-di-p-phenyl-diisocyanate, and hexamethylene-diisocyanate) via condensation reaction. Second, the structures of PAMUs were confirmed by FT-IR, NMR, and UV-Vis spectral analyses. Cyclic voltammetry (CV) was used to determine the electrochemical oxidationreduction characteristics of (PAMU)s. The CV results of PAMUs compounds showed to have an electrochemical band gap below such as 2.0 eV. The PAMUs were characterized by TGA, DSC, SEM, SEC and AFM techniques. TGA analysis results of compounds showed considerable increasing of the thermal stability of polymers, because of finding of azomethine bond in the main chain.

Chemical Oxidative Synthesis and Characterization of Poly(8-hydroxyquinoline) Particles

The chemical oxidative polymerization (OP) of 8-hydroxyquinoline (HQ) in an organic medium leaded to the formation of the C-2 and C-4 linking poly (8-hydroxyquinoline) (PHQ). The structure of PHQ was confirmed by UV-Vis, FT-IR, and 1H-NMR. The characterization of polymer was performed by TG-DTA, differential scanning calorimetry, dynamic mechanical analysis, dynamic light scattering, size exclusion chromatography, X-ray diffraction, cyclic voltammetry, atomic force microscope, photoluminescence and solubility tests. The fluorescence spectrum of PHQ exhibited an emission peak at approximately 525 nm in DMSO. Accordingly, it was found PHQ emitted green light whereas HQ emitted yellow light in DMSO solvent. Optical band gaps (Eg) of PHQ was calculated to be 3.31 eV. The electrical conductivities of iodine doped-PHQ and undoped-PHQ were measured with four-point probe technique. Magnetic particles was prepared by chemical precipitation of mixed Fe(II) and Fe(III) salts and modified with HQ by using an in situ chemical oxidation polymerization method in organic medium.

Synthesis, characterization, electrochemical and surface morphology properties of poly(azomethine-ester)s

In this study, poly(azomethine-ester)s (PAEs) were synthesized via elimination reactions of aromatic dihydroxy compounds containing imine bonding with terephthaloyl chloride. The structures of PAEs containing different aliphatic chains and ether bridges were confirmed by FT-IR, 1H, 13C-NMR and UV-Vis measurements. Electrochemical parameters of the synthesized SBs and PAEs were determined by cyclic voltammetry measurements. Thermal properties of the synthesized monomers and polymers were investigated by TG–DTA, DMA and DSC techniques. Molecular mass distributions of PAEs are determined with gel permeation chromatography measurements. Morphological and topographic properties of the SBs and PAEs containing azomethine linkage in the main chain were investigated by SEM and AFM techniques, respectively. Maximum particle sizes on surfaces of polymers were calculated with AFM analyses. Surface modifications of poly(azomethine-ester)s and maximum particle size on their surface were studied with topographic and 3D AFM images and particular size curves.

Peroxidase/H2O2 catalyzed oxidative oligomerization of 1-aminopyrene

ABSTRACT A new florescent oligo(aminopyrene) (OAP) was successfully synthesized by enzymatic approach. For this, H2O2 and Horse Radish peroxidase (HRP) were used as catalyst and oxidant, respectively. The structures of monomer and oxidation product were confirmed by NMR, FT-IR and UV-Vis measurements. The oxidation product was characterized by gel permeation chromatography (GPC), thermogravimetry (TG), differential scanning calorimetry (DSC), cyclic voltammetry (CV), photoluminescence (PL) and scanning electron microscopy (SEM) analyses. OAP was soluble in a wide range of organic solvents. UV-Vis spectrum of the OAP showed a dramatic red shift compared to that of the monomer. The optical and electrochemical band gaps of OAP were found to be 1.65 and 1.56 eV, respectively. OAP emitted turquoise color in THF and green color in toluene. SEM observations indicated the presence of a heterogeneous cauliflower like morphology.

Synthesis and characterization of a new dyestuff polymer soluble in alkaline aqueous media

Novel dyestuff polymers were successfully obtained through oxidative polymerization technique. The synthesized Schiff base and its polymer were soluble in alkaline aqueous medium and they have various colors in different solutions. Also, it can be said that the synthesized compounds are suitable as coloring agent (dyestuff) for textile applications. Fluorescence properties of the compounds were determined in DMF with different concentrations (mg/L). Poly-tris(4-aminophenyl)methanol (P-TAPM) has quite high emission and excitation intensity values. Optical and electrochemical band gaps of the polymers were lower than those of the monomers indicating the more conjugated structure of the polymers. The oxidized states of the novel dyestuff compounds were examined by cyclic voltammetry (CV) technique. The solid state conductivity measurements showed that the synthesized polymers were semiconductors when exposed to the iodine vapour their conductivities could be increased. P-TAPM had the highest undoped conductivity. Thermal characterizations of the synthesized compounds were carried out by TG-DTA and DSC methods.

Heat resisting and water-soluble chocolate polyesters containing azomethine group

Abstract In this study, soluble in water poly(azomethine-ester)s (PAEs) were synthesized via elimination reactions of aromatic dihydroxy compounds containing imine bonding with terephthaloyl chloride. The structures of Schiff bases (SBs) and PAEs containing different aliphatic chains were confirmed by FT-IR, 1H-NMR, 13C-NMR and UV-Vis analyses. Physicochemical properties of the new polymers were characterized. Thermal properties of the compounds were investigated by TGA-DTA, DMA and DSC. According to TGA measurements, the starting degradation temperatures (Ton) of P-1, P-2, P-3, and P-4 poly(azomethine-ester)s were found as 255 °C, 232 °C, 222 °C, and 221 °C, respectively. The starting degradation temperatures of the poly(azomethine-ester)s were higher than their Schiff base compounds. According to dynamical mechanical analysis (DMA) measurements, glass transition temperature (Tg) of P-1, P-2, P-3, and P-4 poly(azomethine-ester)s were found as 95 °C, 138 °C, 140 °C, and 145 °C, respectively. The morphological and topographic properties of the PAEs containing azomethine linkage in the main chain were investigated by FE-SEM and AFM, respectively. The molecular mass distributions of PAEs were determined by gel permeation chromatography (GPC). Electrochemical (E′g) and optical band gap (Eoptg ) values of the prepared SBs and PAEs were calculated from cyclic voltammetry (CV) and UV-Vis analyses. The electrochemical band gap (E′g) values of P-1, P-2, P-3 and P-4 were found as 2.44 eV, 2.41 eV, 2.39 eV and 2.39 eV, respectively, from the cyclic voltammetry.

Photophysical and thermal properties of polyazomethines containing various flexible units

In this study, the poly(azomethine-ether-urethane), poly(azomethine-ester) and poly(azomethine-epoxyether) compounds were prepared to investigate effect of various flexible units on some physical properties like thermal stability and photophysical properties. Structural characterizations were made by FTIR, 1H NMR, 13C NMR, and UV-Vis analyses. The molecular weight distributions of polymers were performed by gel permeation chromatography (GPC) measurement. The chemical and physical properties of polymers were examined by thermogravimetry (TG), differential scanning calorimetry (DSC), photoluminescence (PL), dynamic mechanical analysis (DMA), scanning electron microscope (SEM) and atomic force microscopy (AFM) techniques. As a result, the outstanding properties related to the photoluminescence and thermal measurements of the polymers were obtained. Therefore, the presented photoluminescent polymers could be used in thermally stable photo-functional materials.