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Modification of Gold Surface by Layer-By Reactive Coating of Polyester-Polyethyleneimine Based Gel
(Izmir Institute of Technology, 2020) Yıldız, Ümit Hakan; Yıldız, Ümit Hakan; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
Polymeric gels defined as soft and solid-like systems that enable to retain a large volume of solvent and their high molecular weight provides long-term stability without crystallization. Therefore, the use of polymeric gels in the fields of energy and sensor technologies has become advantageous. In this thesis, the polymeric gel is successfully synthesized on the gold surface by Aza-Michael addition reaction of the polyester scaffold with a triple covalent bond and branched polyethyleneimine which is a secondary amine source. The polyester-polyethyleneimine based gel was generated on the isocyanate functionalized gold surface by using the grafting-to methodology. The morphology of the surface and thickness of the coating can be adjusted by layer-by-layer reactive coating on the gold surface of polymer structures. Electroactive properties are acquired for different application areas of the synthesized gels. To provide modular electron transfer, polyethyleneimine was modified with ferrocene carboxaldehyde prior to obtaining gel on the surface. The gel interface on the gold surface will increase the surface area and activity due to its three-dimensional structure and adjustable morphology. The number of the immobilized structures, the electroactive species in a unit area and electron transfer increases. The modified electrode surfaces coating yields and electroactivity examined with electrochemical methods, Cyclic Voltammetry and Electrochemical Impedance Spectroscopy. The morphological properties investigated by Atomic Force Microscopy. Additionally, polyester-based gels lithium-ion conductivity was investigated. Dissociation of lithium perchlorate in the gel and enhancing the conductivity was investigated. Indium tin oxide coated glasses were used as an electrode to characterize lithium ion conductivity.
Preparation and Characterization of Calcite (caco3) Particulate Filled Thermoplastic Composites
(Izmir Institute of Technology, 2014) Kızıltepe, Esin; Tanoğlu, Metin; Tanoğlu, Metin; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Nano-sized particle filled polymer composites have been received great attention of researchers and industrial institutions in recent years due to their unique properties, save as high mechanical strength, thermal and solvent resistance as compared to traditional composite materials. In this study, calcium carbonate (CaCO3) filled polypropylene (PP) and Polyethylene (PE) composite blends were prepared using a co-rotational twin screw extruder with a calcite particle content varying from 0 to 30 wt. % . Tensile and three-point bending test coupons were prepared by injection moulding using the extruded composite blends. The effects of calcite reinforcement (with and without stearic acid treatment) on the microstructural, thermal and mechanical properties of neat PP and PE were investigated. Nano-CaCO3 powders were characterized by means of Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The PE and PP were characterized via differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Analytical results were compared with the experimental results.
Characterization of Ultra High Molecular Weight Polyethylene (uhmwpe) Modified by Metal-Gas Hybrid Ion Implantation Technique
(Izmir Institute of Technology, 2006) Urkaç Sokullu, Şadiye Emel; Tıhmınlıoğlu, Funda; Tıhmınlıoğlu, Funda; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
The aim of this work was the characterization of the surface modified Ultra High Molecular Weight Polyethylene (UHMWPE) in order to understand the effect of ion implantation technique on the properties of this material. The samples were Ag and Ag+N hybrid ion implanted by using MEVVA (Metal Vapour Vacuum Arc) ion implantation technique with a fluence of 10 17 ions/cm2, extraction voltage of 30 kV.Untreated and surface treated samples were investigated by Stopping andRange of Ions into Matters (SRIM), Rutherford Back Scattered Analysis (RBS), Attenuated Total Reflection - Fourier Transform Infrared (ATR/FT-IR) Spectroscopy, Raman Spectroscopy, Optical Absorption Photospectroscopy (OAP), Thermo Gravimetry Analysis (TGA), Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD) Analysis, Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Optical Microscopy (OM), Micro-hardness and Contact Angle Measurement. The results of RBS analysis show that Ag ions were detected up to 32 +15 nm after Ag implantation, and 42 +15 nm after Ag+N implantation., underneath the surface. ATR- FTIR chemical characterization analyses results indicated that the effect of implantation on UHMWPE surfaces caused dehydrogenation of polymer with an increase of C.C bond formation which results in enriching the crosslinking carbon atoms on the surface. Optical Absorption Photospectroscopy and Raman spectrum suggests that the chemical structure of UHMWPE has changed after implantation. The characterization results showed that the ion bombardment induced an increase in the % crystallinity, onset and termination degradation temperatures of UHMWPE obtained by thermal analyses, an increase in hardness, and surface wettability and a decrease in roughness of the polymer. The surface topography results can be attributed to the implantation inducing surface roughness decreasing due to the better wettability properties of surfaces obtained after implantation. In conclusion, this study has shown that ion implantation represents a powerful tool on modifying key properties on UHMWPE surfaces.

Master Degree / Yüksek Lisans Tezleri

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