LEE- Kimya-Doktora
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ÖgeExtremely rapid synthesis of polymers and post-polymerization modifications via novel and straightforward methods(Fen Bilimleri Enstitüsü, 2020) Dağlar, Özgün ; Durmaz, Hakan ; 650227 ; Kimya Ana Bilim DalıChemistry as a science, along with the requirements of today's conditions and the scientific developments that have already taken place, present a significant difference in terms of need today, when the foundations of this science were laid. Environmental developments have made it compulsory to act with the awareness of some responsibilities while fulfilling the goals of science. Global warming and climate change, which have been on the agenda of humanity since the 2000s, have started to affect human life more effectively than ever before. As the effects of the deteriorated climate balances are observed, the emergence of damage to the environment made it necessary to take some precautions in the field of chemistry, as in many other disciplines. The concept of "green chemistry", based on this idea, contains some basic working principles that will keep the environmental damage to a minimum. According to green chemistry; environmental damage can be reduced or even made almost harmless by some method changes. In this context, the use of non-toxic, safe, and renewable chemicals, the design of atom efficient and energy-saving reactions, and preferably the use of non-metal catalysts are recommended. Also, the use of non-toxic green solvents or even solvent-free reactions are being encouraged. Although the systems where all of them can be carried out at the same time are not very easy to conduct, many reactions are seen to be carried out by fulfilling these requirements, albeit partially. In this thesis, which is expected to make a great contribution to the literature, the criteria of green chemistry have been taken into consideration. However, very important and interesting findings were obtained by integrating nucleophilic addition reactions, one of the most interesting topics of organic chemistry, into polymer chemistry. In the study carried out in the second chapter of the thesis, the modifications of a polyester structure containing a reactive double bond with various thiol and amine compounds were focused. The compound, namely 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD), which is a strong nucleophilic and basic catalyst, was determined as the most suitable catalyst to be used in the rest of the study. In this study, the polyester structure containing reactive double bond was modified in chloroform (CHCl3) solution in a short time like 1 minute in the presence of TBD with various thiol compounds. The reaction results were supported by 1H NMR, 13C NMR, DSC, and GPC analyses. It was determined that the polymer modifications obtained were approximately 100%. Following these modifications with thiols, the polymer was tried to be modified with amines without using an extra catalyst. It was found that the maleate structure in the polyester backbone transforms into fumarate without any addition reaction after the polymer was treated with diethylamine. In the third chapter, the dimethyl acetylenedicarboxylate structure, which has a reactive triple bond and which we call DMADC in this study, was treated as a monomer and polymerized with dithiol compounds, by experimenting with various amidine and guanidine bases as catalysts. Among these catalysts, TBD has come to the fore as the catalyst that provides the most efficient polymerization. After determining the optimum polymerization conditions, various dialkyl acetylenedicarboxylates and dithiols were reacted to synthesize polythioethers with different properties. The polymerization mechanisms were revealed and characterizations of the polymers were performed using 1H NMR, 13C NMR, FTIR, TGA, DSC, and GPC analyses. Subsequently, propiolate structures, having only one electron-withdrawing group, were reacted with 1,6-hexanedithiol and polymerization behaviors were examined. Following the synthesis of new types of linear polythioethers, using the same method, a series of experiments were carried out for the synthesis of hyperbranched polymers, which we can refer to as a different topological analogue of these two structures containing an electron-deficient triple bond. DMADC and methyl propiolate structures used in the linear study were reacted separately with trimethylolpropane tris (3-mercaptopropionate) compound, which we can refer to as trithiol, in the presence of TBD in CHCl3, and A2B3 type polymers were synthesized. Various catalysts and reaction conditions were tried to determine the most suitable polymerization conditions and analyzes were performed depending on the reaction time. In the fifth chapter, the polymerization study presented to the literature as a simple and new method is intended to be used in an application. For this, acetylene dicarboxylic acid compound, which is an electron-deficient structure, is esterified with fatty alcohols with long chains to form ester monomers of different lengths. In this study, based on the idea that the known thermal energy storage properties of long fatty alcohols can be used as phase-change materials, also known as an insulating material, electron-deficient alkyl acetylenedicarboxylate compounds with different chain lengths were polymerized and the resulting polymers were analyzed. These materials, which were tested for leakage, whose thermal stability and phase change properties were examined, gave similar results with other phase change materials used in the literature. The synthesis of fluorine-containing polymers is always privileged in polymer chemistry. It has always been interesting to discover alternative new methods for the synthesis of such polymers, which are normally difficult to obtain. In the sixth chapter of the thesis, a study on the synthesis of new types of fluorinated polythioethers have been carried out. The compound, namely ethyl 4,4,4-trifluoro-2-butynoate, which we encounter as an analogue of DMADC, has been polymerized with various dithiols using TBD as a catalyst. Contrary to the difficulty in polymerization conditions of other structures containing CF3- group, in this study, polymerizations have been successfully accomplished in extremely soft conditions, with high yields, high efficiencies, high molecular weights, and in a relatively short time. The mechanism of polymerization was illuminated, characterizations of the resulting polymers were carried out by 1H NMR, 13C NMR, 19F NMR, FTIR, TGA, DSC, and GPC. At the same time, since the fluorinated polymers show different surface properties compared to other types of polymers, the contact angle measurements were examined to determine the hydrophobicity of the polymer and high contact angle values were found as expected from the hydrophobic surfaces. In order to obtain detailed information on the surface properties of polymers, topographic morphologies of polymers were examined and homogeneous surfaces were observed without any deflect. As a result of these studies, new types of fluorine-containing polymers have been presented to the literature with a new synthesis method. Within the scope of this thesis, many researches, experiments, and applications have been carried out considering the requirements of green chemistry and the needs of the literature. The studies carried out in each section of the thesis have been published in highly respected international journals in the polymer fields. Great experiences have been obtained from all the studies carried out, and also these studies; received three separate project supports (TGA-2019-42295 and TDK-2018-41700), one of which is the TUBITAK 1001 (118Z319) project.