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    Antibacterial glass films prepared on metal surfaces by sol-gel method
    (Springer, 2010) Kiraz, Nadir; Kesmez, Omer; Burunkaya, Esin; Budama, Leyla; Acar, Burcin; Asilturk, Meltem; Camurlu, H. Erdem
    This paper describes the preparation and characterization of glass films consisting of SiO2, Li2O, Na2O, K2O or MgO in varying compositions on stainless steel and aluminum substrates by sol-gel method. Silver phosphate or silver incorporated zeolite was also introduced into the sols for obtaining antibacterial effect. The SiO2/Li2O/Na2O system having the composition of 85:5:10 wt% was found as the optimum for obtaining a stable sol and film formation. The films were investigated by scanning electron microscopy (SEM) and electron dispersive analysis by X-ray (EDX), Fourier transformed infrared (FTIR) spectroscopy, thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA). Homogenous films having 300 +/- A 20 nm thicknesses were formed by spin coating and then by curing at 500 A degrees C for 1 h. Obtained films had high adherence to the metal substrates and they were also durable in acidic, basic or NaCl environments. They also presented a powerful antibacterial effect against E. coli.
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    Effect of acid, water and alcohol ratios on sol-gel preparation of antireflective amorphous SiO2 coatings
    (Elsevier Science Bv, 2011) Kesmez, Omer; Burunkaya, Esin; Kiraz, Nadir; Camurlu, H. Erdem; Asilturk, Meltem; Arpac, Ertugrul
    Varying amounts of nitric acid catalyst, water and ethyl alcohol were used in the preparation of SiO2 sols by hydrolysis and condensation reactions of tetraethyl orthosilicate in a one step acid catalysis process. Hydrolysis of TEOS was followed by FT-IR analyses. Size of SiO2 particles was seen to vary in 8-41 nm range with respect to changing HNO3 and water amounts in the sols. Gelation occurred in some systems. Surfaces of films were examined by FESEM and AFM, after coating on glass substrates by dip coating. Thicknesses of the films were measured to be in the range of 80-120 nm. 5.6 +/- 0.2% point increase in light transmittance was obtained when HNO3/TEOS (mol/mol) ratio of 4.74 x 10(-4) and H2O/TEOS (mol/mol) ratio of 9.08 were utilized. Sols were found to be stable for months and coatings prepared after 45 days still provided 5.2 +/- 0.2% point increase in light transmittance. (C) 2011 Elsevier B.V. All rights reserved.
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    Effect of amine catalysts on preparation of nanometric SiO2 particles and antireflective films via sol-gel method
    (Springer, 2010) Kesmez, Omer; Kiraz, Nadir; Burunkaya, Esin; Camurlu, H. Erdem; Asilturk, Meltem; Arpac, Ertugrul
    SiO2 sols were prepared by hydrolysis and condensation reactions of tetraethyl orthosilicate through a one step acid or a two step acid + base catalysis process, in the presence of nitric acid and four different base catalyzers, namely trimethylamine, triethylamine, tripropylamine and tributylamine. Hydrolysis of TEOS was followed by FT-IR analyses. Particle size distributions of the sols were evaluated after predetermined durations in 1-22 days. Particle growth was seen to be faster in amine catalyzed systems than in one step acid catalyzed system. The highest rate of growth was in triethylamine catalyzed system. Glass substrates were dip coated with the prepared SiO2 sols. Effect of sol aging duration on film thickness and on light transmittance properties of the films was investigated with respect to type of base catalyst. Thicknesses of the films which were measured to be in the range of 100-400 nm, were seen to increase with aging duration of the sols. Triethylamine catalyzed system presented the highest film thickness. Films obtained from one step acid catalyzed system presented an increase of 4.8%; whereas acid + base catalyzed films provided an increase in the light transmittance of 5.7% in the first 4 days of aging. Surfaces of films were examined by FESEM and AFM. The antireflective character of the films was verified by diffuse reflectance analyses.
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    Hydrophilic hybrid SiO2:polyethylene glycol-3-isocyanato-propyltrietoxysilane nanocomposite films
    (Elsevier Science Sa, 2012) Burunkaya, Esin; Kesmez, Omer; Kiraz, Nadir; Camurlu, H. Erdem; Asilturk, Meltem; Arpac, Ertugrul
    SiO2:polyethylene glycol (PEG)-3-isocyanato-propyltrietoxysilane (IPTES) hydrophilic films were prepared from PEG having various average molecular weights, namely 200, 400 and 600; SiO2 nanoparticles, and tetraethyl orthosilicate (TEOS) through sol-gel method. SiO2 nanoparticles were utilized in various amounts to enhance the mechanical properties and hydrophilic character of the films. Films were characterized by Fourier transformed infrared spectroscopy, field emission scanning electron microscopy, atomic force microscopy, adhesion test, humidity test and water contact angle (WCA) measurements. Thicknesses of the obtained films were about 800 nm. Incorporation of TEOS enhanced adhesion of film to substrate as well as improving stability of the film against water. WCA was seen to decrease, and porosity and surface roughness was seen to increase with increase in SiO2 nanoparticle content of the films. Increase in PEG molecular weight also resulted in a decrease in the WCA, thus WCA as low as 15 degrees was obtained. (C) 2012 Elsevier B.V. All rights reserved.
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    Preparation of aluminum-doped zinc oxide (AZO) nano particles by hydrothermal synthesis
    (Springer, 2010) Burunkaya, Esin; Kiraz, Nadir; Kesmez, Oemer; Camurlu, H. Erdem; Asilturk, Meltem; Arpac, Ertugrul
    Aluminum doped zinc oxide (AZO) nanometric particles were synthesized by hydrothermal method. Aluminum nitrate hydrate, aluminum sec-butoxide and zinc nitrate hydrate were used as the starting materials, and n-propanol and 2-butanol were used as solvents. Ratio of Al2O3 in ZnO was kept at 10 wt%. Reaction was conducted in a Teflon autoclave at 175-225 A degrees C for 5 h. Ratios of alcohol, H2O and HCl to zinc nitrate hydrate were altered and 6 different sets of parameters were investigated. Obtained products were subjected to powder-XRD, particle size measurement, TEM examination and AAS analysis. Single phase AZO particles were obtained at alcohol to zinc nitrate ratio of 35, acid to zinc nitrate ratio of 0.2, at 225 A degrees C. Particle size was determined as 3.2 +/- A 0.4 nm from TEM examinations and as 1-2 nm from dynamic light scattering. Synthesized particles have amphiphilic character, thus they can be dispersed in both polar and non-polar media. It was seen from the UV-diffuse reflectance spectra that the AZO powder had low reflectance in the UV region and high reflectance in the visible region. The obtained powder has the potential to be utilized in the form of thin films for optical and electronic purposes.
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    Sol-gel synthesis of 3-(triethoxysilyl)propylsuccinicanhydride containing fluorinated silane for hydrophobic surface applications
    (Springer, 2010) Kiraz, Nadir; Burunkaya, Esin; Kesmez, Omer; Asilturk, Meltem; Camurlu, H. Erdem; Arpac, Ertugrul
    In this paper, novel fluorinated silane compound was prepared by adding hydroxyl terminated Fluorolink D10H oligomer to 3-(triethoxysilyl)propylsuccinicanhydride. The obtained silane system was independently composed with 3-Aminopropyltrimethoxysilane, 3-Glycidyloxypropyltrimethoxysilane and 3-Glycidyloxypropyltriethoxysilane and, then the prepared coating solutions were applied to glass surface by spin-coating method. The chemical bonding between groups in system was investigated by Fourier Transform Infrared Spectroscopy analyses. The elemental composition of coatings was determined using Energy Dispersive X-ray Spectroscopy analyses. Its structure and surface properties were analyzed by scanning electron microscopy, atomic force microscopy, contact angle measurement and Ultraviolet-visible Absorption Spectroscopy. The amounts of fluorine on the coatings prepared with GF20-D10H-AMMO, GF20-D10H-GLYEO and GF20-D10H-GLYMO are 31, 32 and 34% at, respectively. Transparent coatings with smooth surface and uniform thickness were observed. The coatings had nanoscale roughness. The contact angles of coatings for water ranged from 88 to 107(o), and that of n-hexadecane ranged from 53 to 60(o).
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    Sol-gel synthesis of IPTES and D10H consisting fluorinated silane system for hydrophobic applications
    (Springer, 2010) Burunkaya, Esin; Kiraz, Nadir; Kesmez, Omer; Asilturk, Meltem; Camurlu, H. Erdem; Arpac, Ertugrul
    In this study, new fluorinated silane system was prepared by adding hydroxyl terminated Fluorolink D10H oligomer to 3-isocyanatopropyltrietoxysilane. The obtained silane system was independently composed with 3-Glycidyloxypropyltrimethoxysilane and 3-Glycidyloxy-propyltriethoxysilane. Then the prepared two different coating solutions were applied to glass surface by spin-coating method. The chemical bonding between groups in system was investigated by FTIR analysis. The elemental composition of coatings was determined by using EDX analysis. Their structure and surface properties were analyzed by scanning electron microscopy, atomic force microscopy, contact angle measurement and UV-vis spectrophotometer. The amounts of fluorine on the coatings prepared with IPTES-D10H-GLYEO and IPTES-D10H-GLYMO were 33 and 34 %wt, respectively. Transparent coatings with smooth surface and uniform thickness were obtained. The coatings had nanoscale roughness. The contact angles of coatings for water were range from 103A degrees to 110A degrees, and for n-hexadecane were range from 59A degrees to 62A degrees.