Preparation and Investigation of Polymeric Mixtures | Author : Anil Yesildag, Nurseli Uyanik | Abstract | Full Text | Abstract :It is common that, in order to make the brittle nature of PS better, they are blended with saturated polymers, although there are many different methods available. Polypropylene (PP), on the other hand, is a semi-crystalline, commercial, and thermoplastic polymer belonging the family of polyolefins. In general, commercial PP is isotactic (i-PP). PP can be produced with Ziegler-Natta initiator/catalyst system, as well as metallocene catalysts. Metallocene (m), as an initiator/catalyst system, one can produce polypropylene in the desired molecular weight range, and the molecular weight distribution of this material (mPP) is narrower. Polypropylene has a more saturated structure than polystyrene. However, PS and PP polymers are not of blendable nature. If the blend is not homogeneous in the micro-phase, the desired advantages in the properties cannot be achieved, and regulators are needed to be incorporated into these type of polymers
In this study, molten blends of PS and mPP were prepared in an extruder. The effect of different regulators in the final product, by adding 70% PS and 30% mPP, and 5 phr, was investigated by mechanical and thermal characterization methods. In addition, molten flow index measurements helped investigate the handling of these samples. For comparison, the mixture which did not contain a regulator was also prepared and this sample was subjected to same characterization techniques. We have observed that one of the regulators used in this study had a more pronounced effect. |
| Determination of Trace Elements in Deodorant and Mascara Samples with Atomic Absorption Spectrophotometry | Author : Merve Yildirim | Abstract | Full Text | Abstract :Cosmetics are chemical compounds with quite complex structures and therefore, their effects after use on human health is of great importance. Today, when the use of cosmetic products is considered, the contents of them is of utmost importance. Therefore, it is needed to determine the trace element content of cosmetic products and being kept under control. This study reports about the determination of trace elements found in several deodorant and mascara samples with Graphite Furnace Atomic Absorption Spectrophotometry. |
| Synthesis and Characterization of Donor-Acceptor Copolymers Having Dithienophene – Benzothiadiazol Moieties Suitable for Use in Solar Cells | Author : Mertcan Özel, Ipek Ösken, Turan Öztürk | Abstract | Full Text | Abstract :Since the discovery of conducting polymers, researches have been focused on the design and synthesis of new type polymers for development of novel conductive materials. Wynberg et al. have discovered donor-acceptor copolymers and this event has received a great deal of interest. The most important feature of these copolymers is that the band gaps are lowered because of the delocalization of p electrons over electron-donating and electron-accepting groups. For this purpose, several donor and acceptor groups were introduced and they have been concluded to be suitable for light emitting diodes (LEDs) and solar cells. Dithienothiophenes, comprising three fused thiophene rings, have a quite rich electronic structure and therefore, they are expected to show a donor-type behavior. Recently, better donor-type groups were discovered when compared to the ones in the past and their properties were investigated in terms of usability in solar cell applications. In this study, we have synthesized and characterized DTT-Btz-containing donor-acceptor copolymers. |
| Synthesis of a Thienothiophene Derivative Having a Powerful Aggregation-Induced Emission in the Solid Phase, Investigation of Their Electronic and Optoelectronic Properties, and OLED Applications | Author : Bariscan Tahaoglu, Ali Buyruk, Turan Öztürk | Abstract | Full Text | Abstract :For OLED (Organic Light Emitting Diode), development of new organic materials having powerful emission in the solid phase is receiving quite high attention in the academia and technological environment. Studies through this aim has seen through the development of new organic materials, which have powerful aggregation-induced emission, with great hopes. This study reports the design and synthesis of thienothiophene derivatives having both powerful emissive properties and hole (+) carrier features aimed for OLED applications. Their electronic and optoelectronic properties were investigated and the appropriate compounds were selected for OLED applications. |
| Chloromethylation of Polysulfone | Author : Zeynep Songur, Metin Acar | Abstract | Full Text | Abstract :Polysulphon is defined as a family of thermoplastic polymers having high performance properties such as excellent thermal and chemical resistance, durability, high resistance to radiation-induced degradation, transparency, high hardness, strength and good electrical characteristics. Thermal stability concerns the highly vibrating and inflexible nature of the diphenylsulphone group. Ether and isopropylidene groups give the chain flexibility and make the polymer more easily processable. Polysulphones with these characteristic properties serve in important areas such as engineering plastics, medical and food service applications, electrical and engineering components and aerospace applications, and electrical and engineering components and aviation applications can be used to produce plastics that are resistant to heat, chemicals, impact and ale . According to the application, there are polysulfones containing different functional groups, and polysulfones containing imidazolium groups are known to be used as thin membranes in fuel tanks. The most commonly used methods for modification are chloromethylation and lithium. For this reason, experiments have been carried out to optimize the chloromethylation of polysulfones in our work.
By 1H-NMR measurement of the purified product of Psf-CH2Cl, the substitution degree of the chloromethyl group in PSF was tried to be found. As a result, the time effect on the chloromethylation of the polysulfone was examined and the conditions of chloromethylation were optimized. According to the results, it is understood that the time has serious effects on the chloromethylation reaction. The effect of temperature and reagent ratios will be examined during the study.
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| Some Synthetic Modifications Employing 6,9-dihydroxy-7a,14a-dihydronaphthofuranofuro [2,1-b]naphthofuran | Author : Sevil Çimir | Abstract | Full Text | Abstract :Naphthofurans and benzofurans are used in drugs because of their biological activity, molecular electronic components, and functional polymers. Moreover, this type of compounds are used to behave as bactericides and fungucides. The aim of this study was to synthesize 6,9-dihydroxymethyl-7a,14c-dihydronaphthofuranofuro-[2,1-b]naphthofuran. So far, in the literature, only ester- and acid-functionalized naphthofuranofurans were observed to use as ligands. With the synthesis of 6,9-dihydroxymethyl-7a,14c-dihydronaphthofuranofuro-[2,1-b]naphthofuran, we aimed to increase the ligand activity of the compound. Therefore, our first step was to obtain 6,9-dihydroxy-7a,14c-dihydronaphthofuranofuro-[2,1-b]naphthofuran. Practical yield was 72.6%. Its melting point was 220 – 222 0C. The subsequent step was about synthesizing 6,9-dicarboxy-7a,14c-dihydronaphthofuranofuro-[2,1-b] from 2,3-dihydroxynaphthalene.
After obtaining the naphthofuran with 60% yield, we reduced the compound with LiAlH4to yield 6,9-dihydroxymethyl-7a,14c-dihydronaphthofuranofuro-[2,1-b]naphthofuran with limited success due to the insolubility of the compound, and attempts to elucidate the structure of the compound were not successful. As an alternative, we tried the same reaction with the corresponding ester of the compound. To do this, we first synthesized the methyl ester of 3-hydroxy-2-naphthoic acid. This compound was further reacted with glyoxal bisulfite to convert to the ester-functionalized naphthofuranofuran compound. Later, we reduced the ring containing the ester functionality and used column chromatography to purify the compound. As a result, we have achieved to obtain the naphthofuranofuran structure having benzylic alcohol functionality. Isolation of the structure, however, is not easy due to the problems with solubility. We are planning to solve this problem by starting from a naphthyl compound having long alkyl chains. |
| Determination of Ca, Mg, and Mn in Tea Samples with Microwave Plasma Atomic Emission Spectrometry | Author : Dilek Akbiyik, Nil Özbek, Süleyman Akman | Abstract | Full Text | Abstract :Tea is one of the oldest and the most common beverages and its elements are quite rich. Studies show that tea and infusion herbal tea samples may have lots of contamination. It is determined that these contaminations may result from the production phase, the soil it grows, fertilizeds used, and from gases emitted to the atmosphere [1]. Depending on the concentrations, these kinds of contaminations may affect human health.
In this study, more than 30 tea samples were solubilized with microwave aid and the Ca, Mg, and Mn concentrations were found with Agilent 4100 MP-OES. Microwave Plasma Optic Emission Spectrometers (MP-OES) have been in the market for about two years in a commercial manner. In these systems, the plasma is generated from the air with nitrogen generator, and thus, there are no such problems like gas cost nor gas changes. Microwave plasma source, triggered by magnetic means, is more advantageous than flame atomic absorption in terms of sensitivity, linear dynamic range, observability, determination limits, and speed. In the study, the suitable emission wavelength was automatically determined for every element, and optimizations for smoke forming pressure and visualization position. Validation of the system was performed with GB10077605 tea standard reference. Detection limit is 1.01 mg.L-1, 2.9 µg L-1, and 1.2 µg L-1 for Ca (616.217 nm), Mg (285.213 nm), and Mn (403.076 nm), respectively. Apart from solubilized samples, same samples were kept in hot water to find the solubilized portion of the elements. |
| Synthesis of BODIPY Molecules Starting from a,ß-Unsaturated Carbonyl Compounds | Author : Rüya Atlibatur | Abstract | Full Text | Abstract :In recent years, fluorescent dyestuffs are receiving a great deal of interest due to their potential use in many application fields. 4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dyestuffs are one of these family of compounds having the mentioned properties and due to their high quantum yield, high solubility, and the possibility of obtaining several functional materials due to the presence of fluorophore groups, they have been a popular topic to study. Because of different photochemical properties of these groups having boron atoms, BODIPY dyestuffs have been on constant use in areas like chemosensors, energy transfer cassettes, solar cells, photodynamic therapy, laser dyes, and biological labelling. In this study, a BODIPY-type molecule was syntheszed from an a,ß-unsaturated carbonyl compound and the product was characterized with fluorescence and 1H-NMR methods. |
| Grafting of Polystyrene into Poly(hedral oligomeric silsesquioxane) (POSS) Molecules | Author : Özden Özcan, Onur Karakoyun, Mehmet Kodal, Güralp Özkoç | Abstract | Full Text | Abstract :In this study, we aimed to improve the thermal properties, its stability, and the distribution of POSS, namely octavinylpoly(hedral oligomeric silsesquioxane), molecules in the polymeric matrix by grafting polystyrene. Being compatible with the selected POSS molecule, the initiator was AIBN and the solvent was toluene. The experimental method employed was solution polymerization. To characterize the grafting of polystyrene into POSS molecules, Fourier-Transform Infrared Spectroscopy (FTIR), differential scanning calorimetry (DSC), and scanning electron microscopy (POM) were used. We have observed that styrene was successfully grafted onto POSS molecule and that the synthesized polymer had an improved distribution in the polymeric matrix. |
| Synthesis of ß-Substituted Calix[4]Pyrroles and Their Salts | Author : Malhun Fakioglu, Ahmet Akar | Abstract | Full Text | Abstract :Calix[4]pyrroles are heterocalixarene analogs that are capable of binding to anionic and neutral substrates, known for a long time, but the anion binding properties have recently been discovered. Calix[4]pyrroles are easy to synthesize and add functional groups. Bu nedenle birçok amaç için kullanilabilirler. Therefore, they can be used for many purposes. They can be used, in chemistry, as a separating medium for anionic and neutral species, and as a useful precursor for specific calixpyridinopyrroles and calixpyridines. In some special studies, under potential interface conditions, calix[4]pyrroles have been synthesized in order to reverse the Hoffmeister tendency, that is, to use as anion extractants. This anionic extraction scheme can be used in known some environmental applications like nuclear industry, reducing surface aqueous eutrophication, etc. Besides, calix[4]pyrrole derivatives, being highly soluble in organic solvents, may be helpful in the therapy of cystic fibrosis as continuous membrane chloride anion carriers.
In this study, it was aimed to synthesize calix[4]pyrrole monocarboxylic acids as derivatives of calix[4]pyrrole and investigation of their tetrabutylammonium salts. Calix[4]pyrrole monocarboxylic acid, having an acidic functional group, and tetrabutylammonium cation were reacted to obtain the intermolecular oligomeric salt structures along with investigation of their properties. |
| Synthesis and Properties of 4-Thieno[3,2-b]thiophene-3-yl-benzonitrile (TT-CN) for ECD Applications | Author : Recep Isci, Ilknur Demirtas, Ipek Ösken, Erdal Ertas, Turan Öztürk | Abstract | Full Text | Abstract :Synthesis of conjugated organic molecules, having electronic and optoelectronic material properties, have gained much importance for use in organic light emitting diodes (OLEDs), organic field effect transistors (OFETs), photodiodes, lasers, and solar cells, and especially recently, for electrochromic devices. Based on the previous studies, it has been suggested that thienothiophene (TT) and its derivatives have displayed properties that are suitable for applications of electrochromic devices.
In this study, we have investigated the properties of 4-thieno[3,2-b]thiophene-3-ylbenzonitrile (TT-CN) synthesized by our research group for applications in electrochromic devices. |
| Zirconium Complexes of a New Schiff Base Ligand Having Pyrrole Units | Author : Salih Tunaliberberler, Ozan Sentürk | Abstract | Full Text | Abstract :The design and synthesis of new transition-metal catalyst precursors is a very important subject that can provide high catalytic activity with low cocatalyst-to-catalyst precursor (pre-catalyst) ratios and allows unprecedented control over the polymer microstructure, producing new polymers with improved polymer properties. The catalytic activity of transition metal Schiff base complexes became compelling in synthesis of commercially important polymers. Schiff base complexes of especially early transition metal ions (Ti, Zr, Hf) are efficient catalysts both in homogeneous and heterogeneous reactions, the activity of these complexes varied with the type of ligands, coordination sites and metal ions. The non-metallocene complexes of zirconium and hafnium so called “post-metallocene” complexes, such as the zirconium and hafnium phenoxyimine complexes, bisimido pyridyl complexes and recently some Schiff Base complexes bearing heterocycle donors such as furan, thiophene and pyrrole are showing high efficiency in olefin polymerization.
In this study, perfluorophenyl ethylenediamine was synthesized by reacting hexafluorobenzene with ethylenediamine in pyridine.
The new Schiff base ligand was synthesized by the reaction between pyrrole-2-carboxaldehyde and perfluoroethylene diamine in chloroform.
The synthesis of novel zirconium complex of Schiff base derivative of pyrrole was achieved by the reaction of the Schiff base with THF adducts of zirconium tetrachloride.
Later, starting from this new ligand a sodium salt and its zirconium complex were synthesized. |
| Coating of Silicon Carbide Surface with Polymers and Investigation of its Material Properties | Author : Öykü Güngör, Nurseli Uyanik | Abstract | Full Text | Abstract :Polystyrene is one of commercial polymers with versatile usage. In order to improve some properties of PS, some additives can be used and production of blends and composites are common as well. These methods, due to the shorter time needed than developing a new material, are preferred. Silicon carbide (SiC) is a semiconductor material with high oxidation resistance and with high thermal conductivity.
In this study, SiC nanoparticles, which are not compatible with PS, are coated with PS to render it compatible and by using these nanoparticles, PS nanocomposited having SiC have been prepared with molten mixing method. For this reason, SiC nanoparticles were first coated with PS. To prevent the agglomeration fo SiC nanoparticles in PS, the coated SiC nanoparticles (PS/SiC) were prepared followed by determination of coating percentage. This characterization was performed with analysis and TGA. Coated SiC particles were added into the extruder without the need of external addition of a compatibilizer and the homogeneity of the molecular distribution was examined. PS was added 4% PS/SiC, extruder outputs were collected and pressed into pellets and films were produced with hot press from these pellets. Similar experiments were performed with SiC particles which were not coated. Thermal, morphologic and mechanical properties of unadultareted PS, composite having 4% PS/SiC, and a sample of PS with 4% uncoated SiC were investigated. These samples revealed that TGA, microscopy and DMA analyses yielded better distribution in PS-coated SiC, along with the observation of better mechanic strength and thermal behavior, and a homogeneous microscopic appearance. |
| The Effect of pH on Cross-Binding of Lipases with Glutaraldehyde | Author : Kübra Boran, Meleknur Asici, Togayhan Kutluk, Nurcan Kapucu | Abstract | Full Text | Abstract :Immobilization is performed in order to preserve the enzymic activity in catalytic processes, to increase the thermal stability, to fortify the physical durability, and enable re-usability. Therefore, the process becomes economically feasible and advantageous due to the repeated usage of enzymes instead of an usage for only one time.
In this study, we investigated the immobilization by cross-binding of Thermomyces Lanuginosus (TL 100L) and Candida antarctica lipases. The effects of the pH value of the medium (7.5 – 9.0) and the amount of glutaraldehyde (2-3 mL) in order to immobilize Lipozyme TL 100L and PEG 600 was used as a precipitating agent. In the immobilization process of Candida antarctica, in which ethanol was chosen to precipitate, the pH of the medium was kept at 7.0 – 8.5 and the ratio of enzyme to precipitating agent (1:10 – 1:18) was investigated. Immobilization was performed with usage of Tris-HCl buffer for 24 hours. Immobilization yields were found to be 97% for Lipozyme TL 100L at pH 8.5 and 3 mL of glutaraldehyde. For Candida antartica, the yield was 93% at the same pH value and 1:14 enzyme / precipitating agent ratio. The immobilized enzymes have the potential to be used as biocatalysts. |
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