İsmet Kaya

3, 4-Dichlorobenzyl methacrylate and ethyl methacrylate system: monomer reactivity ratios and determination of thermodynamic properties at infinite dilution by using inverse gas chromatography

Abstract Copolymers with various contents of 3,4-dichlorobenzyl methacrylate (BzMA) and ethyl methacrylate (EMA) were prepared in 1,4-dioxane solution using 2,2′-azobisisobutyronitrile (AIBN) as initiator at 60°C. The copolymer compositions were determined by 1H NMR analysis. The monomer reactivity ratios were calculated by both Fineman–Ross, and Kelen–Tudos methods. The monomer reactivity ratios were found to be rBMA=0.521±0.019, rEMA=0.847±0.221 (Kelen–Tudos) and rBMA=0.677±0.008, rEMA=1.117±0.209 (Fineman–Ross). The FT-IR, 13C NMR spectra of the copolymers have been discussed. In all other samples thermal degradation proceeded in a single step. A slight increase in thermal stability of the copolymers was observed with increase in BzMA content. Some thermodynamic quantities such as the specific retention volumes, Vg0, weight fraction activity coefficients of solute probes at infinite dilution, Ω 1 ∞ , Flory–Huggins intereaction parameters, χ12∞, between polymers and solvents, the partial molar free energy, ΔG1∞ the partial molar heat of mixing, ΔH1∞, at infinite dilution were determined from the interactions of poly(BzMA-co-EMA) with alcohols, ketones, acetates, aromatics and n-alkanes by inverse gas chromatography method at 130–150°C. All probes are non-solvent for poly(BzMA-co-EMA) (7:93%) and poly(BzMA-co-EMA) (87:13%) at 130–150°C.

SYNTHESIS, CHARACTERIZATION, THERMAL DEGRADATION AND ELECTRICAL CONDUCTIVITY OF OLIGO[2-(THIEN-2-YL-METHYLENE)AMINOPHENOL] AND OLIGOMER-METAL COMPLEXES

The optimum reaction conditions of the oxidative polycondensation of 2-(thien-2-yl-methylene)aminophenol (2-TMAP) has been accomplished by using air O2, H2O2 and NaOCl oxidants in an aqueous alkaline medium between 20°C and 90°C. The structures of the monomer and oligomer were confirmed by FT-IR, UV-Vis, 1H-NMR and 13C-NMR and elemental analysis. TGA-DTA, size exclusion chromatography (SEC) techniques and solubility tests were applied for characterization. The 1H-NMR and 13C-NMR data show that the polymerization proceeded with C–C and C–O–C coupling system from ortho and para positions and oxyphenylene. The number-average molecular weight (Mn), weight-average molecular weight (Mw) and polydispersity index (PDI) values of oligo[2-(thien-2-yl-methylene)aminophenol] (O-2-TMAP) were determined with SEC measurements. Thermal analyses of oligomer-metal complex compounds of O-2-TMAP with Cd+2, Co+2, Cu+2, Zn+2, Fe+2, Zr+4, Ni+2 and Pb+2 ions were investigated in N2 atmosphere in the temperature range of 15–1000°C. The highest occupied molecular orbital and the lowest unoccupied molecular orbital of monomer and oligomer were determined from the onset potentials for n-doping and p-doping, respectively. Optical band gaps (Eg) of 2-TMAP and O-2-TMAP and oligomer-metal complex compounds determined according to UV-Vis measurements. Also, electrical conductivities of O-2-TMAP and its metal complexes measured with four-point probe technique.

Synthesis, Characterization and Anti-microbial Activity of Oligo-N-2-aminopyridinylsalicylaldimine and Some Oligomer-metal Complexes

The oxidative polycondensation and optimum reaction conditions of N-2-aminopyridinylsalicylaldimine using air oxygen, H2O2 and NaOCl were determined in an aqueous alkaline solution between 40–90 °C. Oligo-N-2-aminopyridinylsalicylaldimine (OAPSA) was characterized by using 1H-NMR, FT-IR, UV-vis and elemental analysis. N-2-aminopyridinylsalicylaldimine was converted to oligomer by oxidizing in an aqueous alkaline medium. The number average molecular weight (Mn), weight average molecular weight (Mw) and polydispersity index (PDI) values were found to be 7487 g mol−1, 7901 g mol−1 and 1.06, respectively. According to these values, 70% of N-2-aminopyridinylsalicylaldimine turned into oligo-N-2-aminopyridinylsalicylaldimine. During the polycondensation reaction, a part of the azomethine (–CH=N–) groups oxidized to carboxylic (–COOH) group. Besides, the structure and properties of oligomer-metal complexes of oligo-N-2-aminopyridinyl salicylaldimine (OAPSA) with Cu (II), Ni (II), and Co (II) were studied by FT-IR, UV-vis DTA, TG and elemental analysis. Anti-microbial activities of the oligomer and its oligomer-metal complexes have been tested against C. albicans, L. monocytogenes, B. megaterium, E. coli, M. smegmatis, E. aeroginesa, P. fluorescen and B. jeoreseens. Also, according to the TG and DTA analyses, oligo-N-2-aminopyridinylsalicylaldimine and its oligomer-metal complexes were found to be stable thermo-oxidative decomposition. The weight loss of OAPSA found to be 20%, 50% and 98% at 350 °C, 535 °C and 1000 °C, respectively.

Synthesis of Metal-Coordinated Poly(azomethine-urethane)s: Thermal Stability, Optical and Electrochemical Properties

In this study, the novel thermally stable metal-coordinated-poly(azomethine-urethane)s (PAMU-M)s were synthesized to investigate some physical properties such as thermal stability, optical and electrochemical properties. For this reason, we firstly synthesized the Schiff base via condensation reaction of p-phenylenediamine with 2,4-dihydroxy benzaldehyde. Secondly, metal-coordinated Schiff bases were synthesized by coordination reaction of the obtained Schiff base and different metal ions such as Cu(II), Ni(II), Pb(II) and Zn(II). Then, these metal-coordinated Schiff bases were converted to their PAMU derivatives by the step-polymerization reaction using 2,4-toluenediisocyanate. Also, thermal stability, electrochemical and optic properties of the obtained materials were investigated.Graphical Abstract

Study of Some Thermodynamic Properties of Poly (3,4-dichloro benzyl methacrylate-co-ethyl methacrylate) Using Inverse Gas Chromatography

Thermodynamic quantities were obtained for the interactions of poly (3,4-di-chloro benzyl methacrylate-co-ethyl methacrylate) poly (BMA-co- EMA) with alcohols, ketones, acetates, aromatics and alkanes by the inverse gas chromatography method at different temperatures. The specific retention volumes, V g ○, the sorption enthalpy, ΔH 1 s , sorption free energy, ΔG 1 s , sorption entropy, ΔS 1 s , weight fraction activity coefficients of solute specimens at infinite dilution, Ω 1 ∞, Flory-Huggins interaction parameters, X∞ 12 , between the polymers and solvents were deteniiined. The partial molar free energy, ΔG 1 ∞, the partial molar heat of mixing at infinite dilution and the solubility parameters of the polymer, δ 2 , were calculated at different temperatures. The glass transition temperatures, T g , of poly (BMA-co-EMA) (18:82,%), poly (BMA-co-EMA) (30:70,%), poly (BMA-co-EMA) (40:60,%) and poly (BMA-co-EMA) (73:27,%) were found to be about 58°C, 59°C, 61°C and 63°C, respectively, as determined by differential scanning calorimetry (DSC). Alcohols, ketones, acetates, n-alkanes and aromatics were found to be nonsolvents for poly (BMA-co-EMA) at this temperatures. Also the solubility parameters for poly (BMA-co-EMA) (18:82,%) and poly (BMA-co-EMA) (40:60,%) at infinite dilution were also found by plotting the graph of [(δ 1 2 /RT)-X∞ 12 /V 1 ] versus solubility parameters, δ 1 , of these specimens.

Photophysical, Electrochemical, Thermal and Morphological Properties of Polyurethanes Containing Azomethine Bonding

In this paper, three new low band gap Schiff bases were prepared by using 3-etoxy-4-hydroxybenzaldehyde and different o-phylene diamines. Then, these Schiff bases were converted to low band gap polyurethane derivatives, and their photophysical, electrochemical, thermal, mechanical and morphological properties were investigated. Photophysical properties of the compounds were investigated by using UV-Vis and photoluminescence (PL) spectroscopy. Electrochemical properties of Schiff bases and polyurethanes containing azomethine were investigated by using cyclic voltammetry (CV). Thermal decomposition and transitions were determined by using TG-DTA, DMA and DSC techniques, respectively. Morphological properties of the compounds were also determined by using scanning electron microscopy (SEM). SEM images showed that polyurethanes containing azomethine consist of semi-crystalline particles.

Synthesis, characterization, and thermal degradation of new aromatic poly(azomethine-urethane)s and their polyphenol derivatives

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, TG-DTA, 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.

Synthesis, Characterization and Thermal Degradation Oligomer and Monomer/Oligomer Metal Complex Compounds of 2‐Methylquinolin‐8‐ol

The oxidative polycondensation of 2‐methylquinolin‐8‐ol (2‐MQ) has been accomplished by using H2O2 oxidant in aqueous alkaline medium. Optimum reaction conditions of the oxidative polycondensation and the main parameters of the process were established. At optimum reaction conditions, yield of the products was found to be 32.0%. The structures of the obtained monomer and oligomer were confirmed by FT‐IR, UV‐vis, 1H‐NMR, 13C‐NMR and elemental analysis. The characterization was made by TG‐DTA, using size exclusion chromatography (SEC) and solubility tests. The FT‐IR, 1H‐NMR and 13C‐NMR data shows that the polymerization proceeded by the C‐C coupling of ortho and para positions according to ‐OH group of 2‐MQ. The molecular weight distribution values of the product were determined by SEC. The number‐average molecular weight (Mn), weight‐average molecular weight (Mw) and polydispersity index (PDI) values of O‐2‐MQ were found to be 1980, 3312 and 1.681 for H2O2 oxidants, respectively. Thermal analysis results of O‐2‐MQ demonstrated to be stability against thermal decomposition. Thermal analyses of 2‐MQ‐Cd, 2‐MQ‐Co, 2‐MQ‐Cu, 2‐MQ‐Zn, O‐2‐MQ‐Cd, O‐2‐MQ‐Co, O‐2‐MQ‐Cu, and O‐2‐MQ‐Zn monomer/oligomer‐metal complex compounds were investigated in a N2 atmosphere between 15–1000°C.

Synthesis, Characterization, and Optimum Reaction Conditions of Oligo-3-Aminopyridine and its Schiff Base Oligomer

Abstract The products and the oxidative polycondensation reaction conditions of oligo-3-aminopyridine with H2O2 and NaOCl were studied. In this reaction, NaOCl was observed to be more active than H2O2 and optimum reaction conditions were determined. Oligo-3-aminopyridine (OAP) was synthesized from the oxidative polycondensation of 3-aminopyridine (AP) with NaOCl and H2O2 in an aqueous acidic medium at 25°–90°C. The products were characterized by 1H NMR, FT-IR, UV-Vis, and elemental analysis. The number-average molecular weight, weight-average molecular weight, and polydispersity index values of OAP synthesized were found to be 250, 800 g mol−1, and 3.20, respectively, using NaOCl, and 240, 840 g mol−1, and 3.50, respectively, using H2O2. The respective values of the Schiff base were 1140, 5190 g mol−1, and 4.55. At optimum reaction conditions, yields of the reaction products were 80.1% (H2O2) and 82.0% (NaOCl). About 90% AP was converted into OAP. TG analyses showed that OAP was stable towards thermo-oxidative decomposition. The weight loss of OAP was found to be 5, 50, and 92 at 125°, 617°, and 1000°C, respectively. The weight loss of oligo-aminopyridinylazomethinephenol (OAPAP) was found to be 5, 50, and 80.50 at 175°, 660°, and 1000°C, respectively. Also, a new oligomeric Schiff base was synthesized from the condensation of OAP with salicylaldehyde and their structures and properties were determined.

Synthesis and characterization of conjugated polyphenols derived from azomethine formation containing terephtaldehyde via oxidative polycondensation

ABSTRACT Preparation of conjugated aromatic polyimines, containing phenols in the backbone and side group substitutions, has been successfully achieved by a chemical oxidative polycondensation of a series of Schiff bases using NaOCl as the oxidant at optimum reaction temperature of 90°C. The molecular structures of synthesized compounds were verified by the FT-IR, UV-Vis, 1H-NMR and 13C-NMR techniques. Using thermogravimetric analysis-differential thermal analysis (TG-DTA) and size exclusion chromatography (SEC), the molecular weight distribution parameters and the characterization of all compounds could be specified. The initial degradation temperatures of the polymers were found in the range of 170–271°C. DSC analyses of the polyazomethines (PAMs) were carried out to assign the glass transition temperatures (Tg). UV-Vis measurements gave information about the optical (Eg) band gaps. Fluorescence measurements were carried out to obtain the maximum PL intensities. The spectral analysis outcome signified a blue and a green light emission behavior when irradiated at different wavelengths. Cyclic Voltammetry (CV) was an effective method to explore the HOMO and LUMO energy levels and electrochemical () band gaps of the polymers. The HOMO energy levels of the synthesized polyimines were lower than those of the monomers indicating the more conjugated structures of the polymers. Four-point collinear probe was used to determine the electrical conductivities of both doped and undoped states of the synthesized polymers with respect to doping time with iodine. The morphological properties of the polymers were illustrated using Scanning Electron Microscopy (SEM) images at different amplifications.