Süleyman Köytepe

Synthesis, Characterization of a New Organosoluble Polyimide and Its Application in Development of Glucose Biosensor

A new aromatic organosoluble polyimide was synthesized from the 4,4′-Diaminodiphenileethane with 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) via a conventional two-stage process. This polymer showed good solubilities in N-methyl-2-pyrrolidone and m-cresol. The polyimide was characterized by FT-IR, GPC, TGA, DSC and DTA, with intrinsic viscosity and adhesive properties also being evaluated. Then, glucose oxidase (GOD) enzyme was immobilized into aromatic organosoluble polyimide by two different methods. It was demonstrated that the poly[4,4′-Diamina very promising substrate for the immobilization and stabilization of enzymes and the development of highly stable biosensors.

Synthesis and properties of novel polyimides from dichloro (1,3-p-dimethylaminobenzylimidazolidine-2-ylidene) p-cymene ruthenium (II)

A novel diamine derivative, dichloro (1,3-p-dimethylaminobenzylimidazolidine-2-ylidene) p-cymene ruthenium (II), bearing a potential site for imide formation, was prepared starting from p-dimethylaminobenzaldehyde. It was used as a monomer to prepare polyimides with several dianhydrides via a one-stage procedure without going through tedious steps. The polyimides have inherent viscosities that range from 1.18 to 1.24 dl/g in N-methyl-2-pyrrolidinone at 30°C. These new polymers are soluble in polar aprotic solvents. The polymeric catalyst was added to (Z)-3-methylpent-2-en-4-yn-1-ol without a solvent and the pure furan was isolated by distillation under reduced pressure and GC determined the conversion of the starting enynol.

Poly[tris((p-aminophenoxy)phosphineoxide)-3,3′,4,4′-benzophenonetetracarboxylicdiimide] as a New Polymeric Membrane for the Fabrication of an Amperometric Glucose Sensor

Poly[tris((p-aminophenoxy)phosphineoxide)-3,3′,4,4′-benzophenonetetracarboxylicdiimide] (PAB) was used as an immobilized enzyme membrane for the fabrication of an amperometric glucose sensor. Enzyme immobilization was performed by two different methods and structural morphology of immobilized enzyme membrane was studied by SEM. The amperometric response of the sensor to hydrogen peroxide, formed as the product of the enzymatic reaction, was measured at a potential of 0.7 V in phosphate buffer solution by means of the TB technique. The influence of preparation conditions (polyimide film thickness, enzyme amount) on electrode performance was examined to obtain the optimal experimental parameters. Sensor characteristics (pH, response time, selectivity, stability) of the PAB/GOx/Pt electrode prepared under optimal conditions has been investigated. Results showed that this sensor exhibited a linear range up to 6 mM and a response time of about 60 s. with good stability. When glucose was injected into the PBS solution in the presence of fouling substances (lactose, sucrose, and urea), excellent amperometric responses were observed. Also, it was seen that the PAB/GOx-Pt electrode blocked the signal current of electroactive oxalic acid.

Synthesis, Characterization and Dielectric Properties of Rodlike Zinc Oxide-Polyimide Nanocomposites

Novel polyimide-rodlike zinc oxide hybrid nanocomposite (PI-RL-ZnO) has been developed from the poly (amic acid) with different weight percentages (1, 3, 5 wt%) of using N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc) as aprotic solvents. The prepared zinc oxide-polyimide nanocomposites were characterized for their structure, morphology, and thermal behavior employing Fourier transform infrared spectroscopy (FTIR), scanning electron micrograph (SEM), transmission electron micrograph (TEM), X-ray diffraction (XRD) and thermal analysis (DTA/TGA/DSC) techniques. These studies showed the homogenous dispersion of zinc oxide in the polyimide matrix with an increase in the thermal stability of the composites on zinc oxide loadings. More importantly, we intend to explore the possibility of incorporating ZnO particles through dispersion into the polyimide network to achieve the polyimide hybrid with lower dielectric constant (low-k). The lowest dielectric constant achieved of the PI-RL-ZnO material is 2.82 by incorporating 5 wt% ZnO (pure PI, k = 3.22). The reduction in the dielectric constants of the PI-RL-ZnO hybrids can be explained in terms of creating ZnO particles and the free volume increase by the presence of the ZnO particles resulting in a loose PI structure.

Novel Type of Metal-Containing Polyimides for the Heck and Suzuki–Miyaura Cross-Coupling Reactions as Highly Active Catalysts

Novel palladium (II)-containing polyimides with exceptional catalytic properties for the Heck and Suzuki–Miyaura cross-coupling reactions were prepared from Pd(II)-α-bis(imine) complex and the corresponding dianhyrides. The glass transition temperatures (Tg) of the polymers ranged from 169 to 241°C. The temperatures at which 10% weight loss occurred in air ranged from 415 to 579°C. Polyimides based on the palladium (II) complex were tested for catalytic activity in the Heck coupling reaction between styrene and several aryl halides and the Suzuki coupling reaction between phenylboronic acid and several aryl halides. The negative effects (e.g., expense, low reaction rates, air-sensitivity) experienced by using phosphines, particularly electron-rich phosphines, as catalysts in large scale applications is overcome by using polymer supported catalysis.

Synthesis and stimuli-responsive properties of the phenanthroline based metallo-supramolecular polymers

A series of functional metallo-supramolecular materials based on polyhedral oligomeric silsesquioxane (POSS) and phenanthroline ligand were prepared using a two-step approach. Firstly, using a phenanthroline ligand, an amino-functionalized transition metal complex was prepared by tin(II) chloride. In the second step, this metal complex was subsequently reacted with the octakis(3-chloropropyl)octasilsesquioxane, resulting for the metallosupramolecular polymers bearing POSS structure. All the synthesized compounds were fully characterized by spectroscopic analysis, thermal and electron microscopy techniques. Stimuli responsible properties of metallo-supramolecular materials were also investigated the reversibility upon external factors, such as electrochemical or the addition of competitive complexing ligands by electroanalytic techniques and UV–Vis spectroscopy. The electro- and chemo-responsive properties of the metallo-supramolecular materials were also improved. As a result, prepared phenanthroline-functionalized polyhedral silsesquioxane are good candidates for electronic, opto-electronic, and photovoltaic applications as a smart stimuli-responsive material.

Synthesis of Triazine-Based Polyimide Nanocomposites with Flower-Like ZnO by Microwave-Assisted Solvothermal Technique

Flower-like ZnO nanoparticles were synthesized by microwave-assisted solvothermal techniques in a simple system at 120°C for 5 h with the microwave synthesis method. Polyimide–ZnO nanocomposites were prepared by blending flower-like ZnO and the poly(amic acid). The prepared polyimide-ZnO nanocomposite films were characterized for their structure, morphology, and thermal behavior employing Fourier transform infrared spectroscopy (FTIR), scanning electron micrograph (SEM), X-ray diffraction (XRD), and thermal analysis (DTA/TGA/DSC) techniques. These studies showed the homogenous dispersion of ZnO in the polyimide matrix with an increase in the thermal steadiness of the composite films on ZnO loadings.

Maltose-Containing Polyurethane Films: Synthesis, Characterization, and Their Use for Determination of Dopamine in the Presence of the Electroactive and Nonelectroactive Interferents

A series of polyurethanes were prepared from the maltose-ethylene glycol-diphenylmethane diisocyanate and used to construct a novel polyurethane electrode for the detection of dopamine. The polyurethanes were characterized by FT-IR, differential scanning calorimetry, and thermogravimetric analysis. The intrinsic viscosity and adhesive properties were also evaluated. Selectivity behaviour of films prepared from polyurethane solutions containing 1%, 3%, 5%, and 10% maltose to electroactive and nonelectroactive substances was examined by DPV. The results demonstrated that polymer electrode by 2 µL polyurethane solutions containing 3% maltose was allowed penetration of dopamine while blocking the permeation of ascorbic acid and uric acid through film.

Syntheses and Properties of Metal Containing Polyimides Based on the Gold Carbene Complex

A novel gold carbene complex, bis(1,3-di-p-dimethylaminobenzylimidazolidinylidene) gold(I), was synthesized and polymerized to polyimides in a one-step method with various aromatic dianhyrides. The gold-coordinated polyimides are characterized by IR and NMR (1H, 13C) spectroscopy. The materials have inherent viscosities that range from 1.88 to 2.39 dl/g and show excellent solubility in N-methylpyrrolidone and N,N-dimethylacetamide. The glass transition temperatures of the coordinated polyimides range from 203–265°C and a 5% weight loss in air is observed from 535–578°C. The polymers form dark yellow, tough films that are transparent above 365 nm. The effect of different flexible units on the properties of the polyimides is discussed.

Design of starch functionalized biodegradable P(MAA-co-MMA) as carrier matrix for l-asparaginase immobilization

We prepared biodegradable P(MAA-co-MMA)-starch composite as carrier matrix for the immobilization of l-asparaginase (l-ASNase), an important chemotherapeutic agent in acute lymphoblastic leukemia. Chemical characteristics and thermal stability of the prepared composites were determined by FT-IR, TGA, DTA and, DSC, respectively. Also, biodegradability measurements of P(MAA-co-MMA)-starch composites were carried out to examine the effects of degradation of the starch. Then, l-ASNase was immobilized on the P(MAA-co-MMA)-starch composites. The surface morphology of the composite before and after immobilization was characterized by SEM, EDX, and AFM. The properties of the immobilized l-ASNase were investigated and compared with the free enzyme. The immobilized l-ASNase had better showed thermal and pH stability, and remained stable after 30days of storage at 25°C. Thus, based on the findings of the present work, the P(MAA-co-MMA)-starch composite can be exploited as the biocompatible matrix used for l-ASNase immobilization for medical applications due to biocompatibility and biodegradability.