Browsing by Author "Şakalak, Hüseyin"

Now showing 1 - 7 of 7

Citation - WoS: 14
Citation - Scopus: 13
All-Dry Hydrophobic Functionalization of Paper Surfaces for Efficient Transfer of Cvd Graphene
(WILEY-V C H VERLAG GMBH, 2019) Çıtak, Emre; İstanbullu, Bilal; Şakalak, Hüseyin; Gürsoy, Mehmet; Karaman, Mustafa
In this study, the successful transfer of chemical vapor deposition (CVD)-grown graphene on an ordinary printing paper surface is demonstrated. Pristine paper is not a suitable substrate for graphene transfer because of its fragile and hydrophilic nature against the chemicals used during the transfer process. Two different fluoroalkyl polymers, namely poly(hexafluorobutyl acrylate) (PHFBA) and poly(perfluorodecyl acrylate) (PPFDA) are coated on paper surfaces by an initiated CVD (iCVD) technique to make the paper surfaces hydrophobic. Hydrophobicity is found to be an important factor in order for the graphene to be transferred onto the paper substrate. Although surfaces coated with PPFDA possess better hydrophobicity owing to their longer perfluoroalkyl group and higher roughness, the graphene transfer is found to be more successful on a PHFBA-coated surface. A thin film of PHFBA on the paper surface acts as a prime layer for effective and defect-free transfer of graphene and makes the paper surface ideal and robust during the graphene transfer process. The as-transferred graphene layer on the PHFBA-coated paper surface shows high conductivity values, even after repeated folding and flattening cycles.
Citation - WoS: 14
Citation - Scopus: 14
All-Dry Synthesis of Poly(2-Ethylhexyl Acrylate) Nanocoatings Using Initiated Chemical Vapor Deposition Method
(ELSEVIER SCIENCE SA, 2019) Şakalak, Hüseyin; Karaman, Mustafa
In this study, Poly(2-ethylhexyl acrylate) (PEHA) thin films were deposited on different substrates by initiated chemical vapor deposition (iCVD) technique. Being a long alkyl chain acrylate with a suitably low glass transition temperature, PEHA is an important member of acrylates family, which is used extensively in adhesives, paints, and coating applications. In iCVD, use of the tert-butyl peroxide as an initiator allowed a deposition rate of 155 nm/min at a filament temperature of 280 degrees C. Precursor flow ratios, filament and substrate temperatures were found to be important parameters that effect the deposition rates. The negative relation between substrate temperature and deposition rates implied an adsorption limited kinetics. FTIR and XPS analyses of the deposited films confirmed that the chemical functionality of the EHA monomer preserved well after iCVD. It was also revealed that the as-deposited films are smooth, uniform and optically transparent. PEHA film deposited by iCVD on glass improved the optical transmittance of glass, by acting as an anti-reflection coating due to its suitable refractive index of 1.45.
Başlatıcılı Kimyasal Buhar Biriktirme Yöntemiyle Basınca Duyarlı Yapıştırıcı Üretimi
(Türk Patent Enstitüsü, 2019) Karaman, Mustafa; Şakalak, Hüseyin
Citation - WoS: 28
Citation - Scopus: 25
Initiated Chemical Vapor Deposition of Poly(ethylhexyl Acrylate) Films in a Large-Scale Batch Reactor
(AMER CHEMICAL SOC, 2019) Yılmaz, Kurtuluş; Şakalak, Hüseyin; Gürsoy, Mehmet; Karaman, Mustafa
The present study demonstrates the successful deposition of poly(ethylhexyl acrylate) thin films in a large-scale closed-batch initiated chemical vapor deposition (iCVD) system. A horizontal cylindrical stainless-steel vacuum tank, which is highly utilized in industrial vacuum applications, was used as iCVD reactor. The effects of substrate temperature, precursor ratio, and pressure on the deposition rates were studied, and the results showed that a deposition rate of 315 nm/min can be achieved in a single run at a reactor pressure of 600 mTorr. At a lower chamber pressure of 400 mTorr, deposition rate decreases, whereas film uniformity increases. By carrying out depositions at successive cycles, thicker films could be obtained, without the need for extensive monomer consumption. The yield percentage was found to be 3.5 for the films deposited in closed-batch system at 400 mTorr, which is 35-fold larger than that of the classical iCVD flow system.
Citation - WoS: 71
Citation - Scopus: 80
Roll-To Roll Initiated Chemical Vapor Deposition of Super Hydrophobic Thin Films on Large-Scale Flexible Substrates
(PERGAMON-ELSEVIER SCIENCE LTD, 2020) Şakalak, Hüseyin; Yılmaz, Kurtuluş; Gürsoy, Mehmet; Karaman, Mustafa
In this study, a large-scale roll-to-roll initiated chemical vapor deposition (iCVD) system was developed to allow for coating superhydrophobic thin films on flexible substrates. Poly(hexafluorobutyl acrylate), which possesses a short fluorinated side-chain, was chosen as the hydrophobic finish material, while a commercial porous bamboo fabric was used as the flexible substrate. After iCVD coating, bamboo surface, which is superhydrophilic by its nature, transformed into a superhydrophobic with a water contact angle of 156 degrees without changing its porous and flexible structure. Similar hydrophobic properties were observed against various daily liquids. Complete coverage of as-deposited films on both sides of bamboo surfaces was observed at very high roll speeds up to 225 mm/min, which allow coatings on 20 m(2) flexible substrates in a single run. Large scale contact angle and chemical uniformity of coatings on fabric surfaces were evaluated using contact angle and XPS analyses. (C) 2019 Elsevier Ltd. All rights reserved.
Citation - WoS: 10
Citation - Scopus: 11
Roll-To Vapor Deposition of Hydrophobic and Transparent Nano-Adhesive Polymeric Thin Films on Rigid and Flexible Substrates
(Amer Chemical Soc, 2022) Şakalak, Hüseyin; Yilmaz, Kurtuluş; Gürsoy, Mehmet; Karaman, Mustafa
This paper demonstrates the adhesive and hydro- Rool-to-roll phobic modifications of glass, poly(ethylene terephthalate), and iCVD bamboo fabric surfaces using the initiated chemical vapor deposition (iCVD) process. iCVD of functional thin films is an all-dry and low-temperature alternative to the conventional wet coating processes. The as-deposited film is a terpolymer in which ethylhexyl acrylate and acrylic acid units comprised the pressure-sensitive adhesive (PSA) part, while perfluorodecyl acrylate (PFDA) acted as the hydrophobic part due to its low surface energy fluorinated side groups. The PFDA composition in the iCVD terpolymer can be systematically varied by adjusting the initial gas feed fractions of monomers, as verified from FTIR and XPS analyses. The usage of the initiator tertbutyl peroxide during the depositions resulted in high deposition rates up to 80 nm/min at a filament temperature of 230 degrees C. The as-deposited films possessed high optical transparency with high shear and peel strength values. Depending on the chemical composition, the peel strength values were up to 0.5 N/25 mm on flexible PET substrates. After the coating, the highly porous bamboo surface not only became sticky due to the existence of the thin PSA layer on top but also the became near-superhydrophobic. The application of iCVD coating parameters to deposit hydrophobic PSA on moving large-area substrates under roll-to-roll deposition mode resulted in highly uniform coatings, which shows the potential of iCVD to be operated in industrial scales to functionalize the industrially important flexible substrates.
Citation - WoS: 8
Citation - Scopus: 7
Vapor Deposition of Stable Copolymer Thin Films in a Batch Icvd Reactor
(WILEY, 2021) Yılmaz, Kurtuluş; Şakalak, Hüseyin; Gürsoy, Mehmet; Karaman, Mustafa
This study demonstrates the deposition of poly(ethylhexyl acrylate-co-ethylene glycol dimethacrylate) (P(EHA-co-EGDMA)) copolymer thin films in a batch type initiated chemical vapor deposition (iCVD) reactor. Crosslinked copolymers are desired for many applications because of their high stable properties. iCVD polymers derived by monomers bearing only one vinyl bond are usually linearly structured polymers and hence they are not durable, which is unfavorable for many real-world applications. Robust crosslinked iCVD films can be produced with the help of crosslinkers. In a typical iCVD process, copolymer thin film is produced by constantly feeding monomer vapor and crosslinker into the reactor. The monomer/crosslinker ratio should be precisely controlled for fabrication of reproducible thin films. In order to eliminate problems caused by adjusting the flowrates of precursors, a closed-batch type iCVD reactor was used for the first time in this study to produce copolymer thin films. The variation of precursors' partial pressures allowed control over the copolymer thin film structures. As compared with homopolymer, copolymers showed the better chemical and thermal stable properties. Almost 40% of the copolymer thin film remained on the substrate surface at an annealing temperature of 300 degrees C, whereas the homopolymer film was completely removed at an annealing temperature of 280 degrees C.