Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 4Citation - Scopus: 4Polymer-Bonded Cdte Quantum Dot-Nitroxide Radical Nanoprobes for Fluorescent Sensors(Springer, 2022) Karabıyık, Merve; Ebil, ÖzgençA novel functional polymer-bonded quantum dots (QDs)-nitroxide radical complex was demonstrated. In the first part of the study, the synthesis of polymer thin films via initiated chemical vapor deposition (iCVD), functionalization of polymer thin films with amine functional groups, and attachment of QDs to polymer surface were demonstrated. Fourier transform infrared spectroscopy and energy-dispersive X-ray spectroscopy together with fluorescence spectroscopy studies revealed that aliphatic primary amine (propylamine) was very effective for the functionalization of iCVD deposited poly(glycidyl methacrylate) (pGMA) and its copolymer with diethylaminoethyl methacrylate (p(GMA-co-DEAEMA)) and also QD attachment to functionalized polymer surface. In the second part of the study, the synthesis and attachment of Quantum Dot-4Amino TEMPO (QD-4AT) nanoprobes to functionalized pGMA thin films and feasibility of using them as fluorescent sensor structures were investigated. It was found that high initial 4AT concentration and long (24 h) interaction times are beneficial for nanoprobe synthesis. Electron paramagnetic resonance (EPR) spectroscopy analysis revealed the existence of covalent bond between QD and 4AT when 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide was used during synthesis. EPR analysis together with fluorescence microscopy investigation confirmed the successful attachment of nanoprobes to polymer surface. Time-depended fluorescence quenching analysis revealed that more than 50% reduction in fluorescence intensity within 15 min demonstrating the potential of polymer bonded QD-4AT nanoprobes in various sensor applications.Article Citation - WoS: 8Citation - Scopus: 7Cvd-Deposited Oxygen-Selective Fluorinated Siloxane Copolymers as Gas Diffusion Layers(American Chemical Society, 2022) Cihanoğlu, Gizem; Ebil, ÖzgençCopolymer thin films of 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V4D4), 2-(perfluorohexylethylacrylate) (PFHEA), and 2-(perfluoroalkylethylmethacrylate) (PFEMA) were synthesized via initiated chemical vapor deposition (iCVD) as potential candidates for gas diffusion layers (GDLs) in gas diffusion electrodes (GDEs) for aqueous metal–air batteries. Thin-film GDLs exhibited an average water vapor transmission rate of 7.5 g m–2 day–1 and enhanced oxygen diffusion with oxygen permeabilities as high as 3.53 × 10–15 mol m m–2 s–1 Pa–1 (10.5 Barrer). The electrochemical performance of GDEs fabricated using commercial catalysts, current collectors, and synthesized GDLs was investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and potentiodynamic polarization measurements. The fabricated GDEs exhibited higher oxygen reduction current densities (228.2 mA cm–2) compared to commercial GDEs (132.7 mA cm–2). Copolymer GLDs exhibited an order of magnitude higher oxygen diffusion (39.5 × 10–8 cm2 s–1) in GDEs compared to commercial counterparts (1.84 × 10–8 cm2 s–1). Due to the high oxygen solubility of V4D4 and excellent hydrophobic behavior of PFHEA and PFEMA, their copolymers can effectively promote the diffusion of oxygen and restrict moisture intake, making them ideal materials for GDLs. Combining well-balanced properties of siloxane and fluorinated polymer chemistries, the iCVD process is an excellent low-cost method for the fabrication of GDLs for metal–air battery applications.Article Citation - WoS: 13Citation - Scopus: 14Robust Fluorinated Siloxane Copolymers Via Initiated Chemical Vapor Deposition for Corrosion Protection(Springer, 2021) Cihanoğlu, Gizem; Ebil, ÖzgençHomopolymers of 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V4D4), 2-(perfluorohexyl)ethyl acrylate (PFHEA) and 2-(perfluoroalkyl)ethyl methacrylate (PFEMA) and their copolymers were synthesized via initiated chemical vapor deposition (iCVD). All coatings exhibited excellent adhesion to substrates. The corrosion resistance of iCVD coatings was investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. In addition, chemical durability of various organic solvents and adhesion to the substrate were also evaluated. Tafel polarization measurements in 5 wt% NaCl solution revealed that the corrosion rates as low as 0.002 mpy on zinc substrates can be reached with 250-nm-thick iCVD-synthesized polymers which is lower than previously reported polymer coatings and more than three orders of magnitude lower than bare zinc. EIS analysis coupled with equivalent electric circuits model confirmed that poly(V4D4) and poly(PFHEA) homopolymers show extremely high protection efficiencies (similar to 99%) on zinc, while poly(V4D4-co-PFHEA) copolymer with slightly lower corrosion efficiency (85-91%) provides a better anticorrosion barrier with weight loss reduction by 57 and 45% for copper and zinc, respectively, and with improved chemical and mechanical properties. The results indicate that iCVD process enables fabrication of finely tuned fluorinated siloxane copolymer conformal coatings for corrosion protection on a variety of substrates.Article Citation - WoS: 21Citation - Scopus: 25Quasi-Static and Dynamic Crushing of Empty and Foam-Filled Tubes(Springer Verlag, 2001) Hall, Ian W.; Ebil, Özgenç; Güden, Mustafa; Yu, C.-J.Metallic foam-filled tubes and their empty counterparts have been tested at quasi-static and dynamic strain rates in order to determine their energy absorption capabilities. Data from the Split-Hopkinson Pressure Bar have been used to generate force vs. displacement curves that are somewhat analogous to pseudo-engineering stress-strain curves. Force balance calculations have also been made. These results indicate that, on an equal weight basis, foam-filled tubes offer greater energy absorption capability than empty tubes at quasi-static strain rates. However, the benefit of foam filling does not appear to be extended to strain rates of the order of 200–500 s−1. Force balance calculations are shown to have potential as a method for monitoring the crushing of metallic foams at high strain rate.