Person: ÇAKMAKÇI, EMRAH
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ÇAKMAKÇI
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EMRAH
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Publication Metadata only Allyl Phosphonium Salt-Modified Clay for Photocured Coatings: Influence on the Properties of Polyester Acrylate-Based Coatings(WILEY, 2015) ÇAKMAKÇI, EMRAH; Zeytuncu, Bihter; Cakmakci, Emrah; Kahraman, Memet VezirIn this study, bentonite clay was modified with a phosphonium salt and this modified clay was used to prepare polyester acrylate based coatings to improve their flame retardancy and mechanical properties. Photocured composites were prepared with 1, 2, and 3 wt% phosphonium salt modified clay and for comparison 1 wt% nonmodified clay containing composites were also prepared. Modified clay displayed good dispersion properties due to its increased basal spacing. Composites were characterized by FT-IR and XRD measurements. According to XRD results, it was found that the modified clay was exfoliated in the composites. Furthermore, we investigated the effect of allyl phosphonium salt modified clay on the thermal, mechanical, and flame retardant properties of polyester acrylate based composites coatings. When compared with neat clay containing coatings, modified clay containing photocured coatings exhibited increased modulus and enhanced thermal properties due to increased crosslinking density. Moreover, the presence of the phosphonium salt enhanced the flame retardancy of the polyester based coatings. POLYM. COMPOS., 36:946-954, 2015. (c) 2014 Society of Plastics EngineersPublication Metadata only Quaternary imidazolium-functionalized reactive silica nanoparticles-containing thiol-ene photocured antibacterial hybrid coatings(Elsevier B.V., 2022) ÇAKMAKÇI, EMRAH; Şen F., Kocatürk E., Çakmakçı E., Kahraman M.V.The need for antibacterial coatings is increasing day by day. In this study, coating materials that do not contain antibacterial agents but have antibacterial properties have been developed. First, two different quaternary imidazole compounds were synthesized. Then, silica nanoparticles were modified with these quaternary agents. By using 1%, 3% and 5% modified silica nanoparticles, UV cured coating materials were obtained according to the thiol-ene reaction mechanism. Mechanical, thermal, surface, structural, optical and antibacterial analyzes of the obtained coatings were performed. The analyzes revealed that UV cured antibacterial coating materials have been successfully synthesized and can be used as a new and unique coating material for the coating industry. © 2021 Elsevier B.V.Publication Metadata only Preparation and drug release properties of lignin-starch biodegradable films(WILEY-V C H VERLAG GMBH, 2012) OGAN, AYŞE; Calgeris, Ilker; Cakmakci, Emrah; Ogan, Ayse; Kahraman, M. Vezir; Kayaman-Apohan, NilhanStarch is one of the most commonly available natural polymers which are obtained from agro-sources. It is renewable and abundant in nature. Unfortunately due to its poor mechanical properties and hygroscopic nature, there are some strong limitations to the development of starch-based products. Usually blends of starch are prepared and plasticized with glycerol to improve some of its properties. In this study, lignin was extracted from hazelnut shells and investigated as a potential additive for starch biofilms. The structural characterization of hazelnut lignin was performed by employing UV spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Lignin was blended with corn starch in different ratios to obtain biofilms. Mechanical and thermal properties of the biofilms were enhanced as the lignin amount was increased in the formulations. Water absorption tests were performed at pH 2.0, 4.0, and 6.0. The percent swelling values of the starch/lignin films increased as pH increased. Also, the biofilm exhibiting the best properties was chosen for the drug release studies. Biofilms showed a fast ciprofloxacin (CPF) release within an hour and then the drug release rate decreased. A pH dependent drug release mechanism was also observed according to KoshnerPeppas model. The drug release increased with a decrease in pH.Publication Open Access Eugenol-DOPO: A bio-based phosphorous-containing monomer for thiol-ene photocurable thermosets(2023-01-01) ÇAKMAKÇI, EMRAH; Özükanar Ö., ÇAKMAKÇI E., Sagdic G., Günay U. S., Durmaz H., Kumbaracı İ. V.The adverse health and environmental effects of petroleum-based materials have become a driving force for the fabrication of bio-based monomers. In this study, we synthesized a novel bio-based reactive phosphorus-containing; eugenol-DOPO, which was prepared in one step by the reaction of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and eugenol via Atherton–Todd reaction. Moreover, a diallyl compound was also prepared by using eugenol and piperazine. All monomers were characterized by nuclear magnetic resonance (NMR), mass, and Fourier-transform infrared (FTIR) spectroscopies. Thiol-ene photocured polysulfide thermoset networks were prepared by using these newly synthesized bio-based monomers. Thermal and thermomechanical properties of the thermosets were measured. Photo-crosslinked networks displayed over 88% gel content values. The thermal stability of the networks as well as the resulting char yields were improved as the percentage of eugenol-DOPO was increased in the formulations. The presence of N and P played a synergistic effect and the limiting oxygen index (LOI) values for the thermoset materials were enhanced. We believe eugenol-DOPO is not only a good alternative monomer for the preparation of thermally stable photocurable thermosets, but it is also a suitable bio-based additive for other polymers as well. Graphical Abstract: [Figure not available: see fulltext.].Publication Metadata only DOPO tethered Diels Alder clickable reactive silica nanoparticles for bismaleimide containing flame retardant thiol-ene nanocomposite coatings(ELSEVIER SCI LTD, 2017) OKTAY, BURCU; Oktay, Burcu; Cakmakci, EmrahThe modification of nanoparticles (NPs) with functional groups that render them much more compatible with the polymeric matrices to prepare organic-inorganic hybrid materials is an active area of research. In this work, flame retardant and reactive nanosilica particles were prepared. First, nanosilica particles were coated with aminosilane and then reacted with furfural to introduce Diels Alder clickable sites. Finally, these reactive NPs were phosphorylated by reacting them with 9,10-dihydro-9-oxy-10-phosphaphenanthrene-10-oxide (DOPO). Different amounts of DOPO tethered Diels Alder clickable nanosilica particles (DDAS) were added to a bismaleimide resin containing thiol-ene based liquid pho-tocurable mixture. Bismaleimide acted as a crosslinker between the organic matrix and DDAS NPs. The effects of DDAS on the thermal and mechanical properties and the curing kinetics of the photocured coatings were investigated. The addition of BMI increased the Tg of the coatings from 40 to 78 degrees C with respect to the base formulation. The presence of BMI improved the distribution of DDAS NPs in the organic matrix. Moreover, the thermal and the flame retardancy of the hybrid coatings were improved. While the LOI of the base formulation was found as 21.6%, with the introduction of DDAS NPs the LOI of the hybrid coatings was increased up to 24.1%. (C) 2017 Elsevier Ltd. All rights reserved.Publication Metadata only Preparation and characterization of flame retardant and proton conducting boron phosphate/polyimide composites(ELSEVIER SCI LTD, 2013) ÇAKMAKÇI, EMRAH; Cakmakci, Emrah; Gungor, AtillaIn this study novel flame retardant boron phosphate (BPO4)/polyimide composites were prepared. 4,4'-Oxydianiline (ODA) was reacted with 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) in dimethyl formamide (DMF) and mixed with BPO4 particles to obtain a series of polyamic acids, mean-while, corresponding polyimides were synthesized via the thermal imidization technique. The amount of BPO4 in the composite films was varied from 0 wt% to 10 wt%. The structure, thermal and surface properties of the polyimide films were characterized by means of ATR-FTIR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The flame retardancy of the composite materials was examined by limiting oxygen index (LOI) measurements and UL-94 VTM tests. Result showed that the LOI values of composites increased from 28 to 39. Furthermore, proton conductivity of polyimide films was measured by the four probe technique. The composite membrane containing 3 wt% of BPO4 showed a conductivity of 0.4 mS/cm at room temperature. (C) 2013 Elsevier Ltd. All rights reserved.Publication Open Access Metal-free click modification of triple bond-containing polyester with azide-functionalized vegetable oil: plasticization and tunable solvent adsorption(2022-07-12) ÇAKMAKÇI, EMRAH; Cangul K., ÇAKMAKÇI E., Daglar O., Günay U. S., Hızal G., Tunca Ü., Durmaz H.Pressure from environmental nongovernmental organizations and the public has accelerated research on the development of innovative and renewable polymers and additives. Recently, biobased \"green\" plasticizers that can be covalently attached to replace toxic and migratory phthalate-based plasticizers have gained a lot of attention from researchers. In this work, we prepared an azide-functionalized soybean oil derivative (AzSBO) and investigated whether it can be used as a plasticizer. We covalently attached AzSBO to an electron-deficient triple-bond-containing polyester via a metal-free azide-alkyne click reaction. The thermal, mechanical, and solvent absorption behaviors of different amounts of azidated oil-containing polyesters were determined. Moreover, the plasticization efficiency of AzSBO was compared with the commercial plasticizers bis(2-ethylhexyl) phthalate and epoxidized soybean oil. At relatively lower AzSBO ratios, the degree of cross-linking was higher and thus the plasticization was less pronounced but the solvent resistance was significantly improved. As the ratio of AzSBO was increased, the glass transition temperature of the pristine polymer decreased up to 31 degrees C from 57 degrees C. Furthermore, the incorporation of AzSBO also improved the thermal properties and 20% AzSBO addition led to a 60 degrees C increase in the maximum weight loss temperature.Publication Metadata only Preparation of photo curable highly hydrophobic coatings using a modified castor oil derivative as a sol-gel component(ELSEVIER SCIENCE SA, 2011) ÇAKMAKÇI, EMRAH; Mulazim, Yusuf; Cakmakci, Emrah; Kahraman, Memet VezirModification and use of natural products have gained a lot of interest in recent years due to their environmental friendliness and their availability from different sources. In this study castor oil based photo curable highly hydrophobic coatings were prepared and characterized. Castor oil (CO) was first modified with 3-isocyanato propyl triethoxy silane and then it was hydrolyzed prior to the coating preparation. The resulting precursor was mixed with norbornyl acrylate, hexane diol diacrylate and hydrophobic coatings were prepared with the aid of fluorinated and nonfluorinated alkoxy silane coupling agents. The addition of fluorine showed a significant impact on the properties of the coatings. As the fluorine content was increased in the formulations, flame retardancy and the contact angle values of the coatings increased. The highest amount of fluorine containing coating showed a contact angle of 119 degrees. Then with the addition of nonfluorinatecl alkoxysilane compounds, a contact angle of 130 degrees was reached. Also the effect of post-cure temperature on contact angle values was investigated. (C) 2011 Elsevier B.V. All rights reserved.Publication Metadata only Properties of Thiol-ene Photocurable Highly Hydrophobic and Oleophobic Nanocomposite Coatings on ABS and HIPS Substrates(WILEY-HINDAWI, 2013) ÇAKMAKÇI, EMRAH; Mulazim, Yusuf; Cakmakci, Emrah; Kahraman, Memet V.In this study, thiolene photocurable highly hydrophobic and oleophobic coatings were prepared and characterized. Trimethylolpropane tris(3-mercaptopropionate) and triallyl 1,3,5-triazine-2,4,6(1H,3H,5H)-trione were used for the preparation of the base formulation. Highly hydrophobic and oleophobic coatings were prepared with the aid of a fluorinated acrylate (Fluowet AC 812) and hydrophobic-fumed nanosilica particles. Nanoparticles were added for increasing the surface roughness and also to increase thermal and mechanical properties of the coatings. Coatings were applied on ABS (acrylonitrilebutadienestyrene) and HIPS (high impact polystyrene) substrates. As the fluorine and nanosilica contents were increased in the formulations, flame retardancy, hydrophobicity, and the oleophobicity of the coatings increased. Coatings were found to be highly thermally stable, highly solvent, and chemically resistant. The surface roughness of the coatings increased with the addition of hydrophobic-fumed nanosilica particles. In addition, the relation between the surface energy and the contact angle of the coatings was investigated. (c) 2012 Wiley Periodicals, Inc. Adv Polym Techn 32: E416E426, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.21289Publication Metadata only New horizon in phospha-michael reaction: Ultrafast double addition of P-H bond-bearing nucleophiles to alectron-deficient triple bonds and its use for functional monomer synthesis and polymer modification(2023-01-01) ÇAKMAKÇI, EMRAH; FINDIK, VOLKAN; ERDEM, SAFİYE; Sagdic G., Daglar O., ÇAKMAKÇI E., FINDIK V., ERDEM S., Tunca Ü., Günay U. S., Durmaz H.In this work, a novel, straightforward, robust, fast, and organocatalyst-mediated phospha-Michael reaction (OCPMR) was developed for the addition of phosphorus nucleophiles to electron-deficient alkynes. Several P-H bond-bearing compounds with either fully aliphatic or aromatic units were utilized for this newly developed reaction, and it was found that phosphorous species containing only aromatic groups reacted with activated alkynes within 5 min at room temperature. The reaction led to a fast double-addition of the phosphorous compounds to the triple bond of the alkynes. An in-depth analysis of the reaction mechanism and selectivity of this OCPMR was performed using computational methods. Using the developed method, double-phosphorylated allyl-functional monomers were synthesized and subsequently used for the synthesis of linear and crosslinked polymers via thiol-ene photopolymerization. The thermoset materials exhibited LOI values as high as 26.4%. We also showed that polyesters having electron-deficient triple bonds could be easily functionalized with the P-H bond-bearing compounds. The synthetic method proposed herein promises easy and fast P-C bond formation under mild reaction conditions, and it is a straightforward method for the synthesis of phosphorus-containing monomers, linear or crosslinked polymers, and for polymer post-functionalization. We believe this feature will be of great interest not only to material chemists and polymer scientists but also to organic chemists, pharmaceutical researchers, etc.