Chemical Engineering / Kimya Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/14
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Article Citation - WoS: 9Citation - Scopus: 10Cvd Deposited Epoxy Copolymers as Protective Coatings for Optical Surfaces(MDPI, 2023) Karabıyık, Merve; Cihanoğlu, Gizem; Ebil, ÖzgençCopolymer thin films of glycidyl methacrylate (GMA), ethylene glycol dimethacrylate (EGDMA) and 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V4D4) were synthesized via initiated chemical vapor deposition (iCVD) as protective coatings for optical surfaces. Chemical durability in various solvents, corrosion resistance, adhesion to substrate, thermal resistance and optical transmittance of the films were evaluated. Crosslinked thin films exhibited high chemical resistance to strong organic solvents and excellent adhesion to substrates. Poly(GMA-co-EGDMA) and poly(GMA-co-V4D4) copolymers demonstrated protection against water (<1% thickness loss), high salt resistance (<1.5% thickness loss), and high optical transparency (~90% in visible spectrum) making them ideal coating materials for optical surfaces. Combining increased mechanical properties of GMA and chemical durability V4D4, the iCVD process provides a fast and low-cost alternative for the fabrication of protective coatings.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.