Browsing by Subject "Electrospuns"
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Item Open Access Bi2O3 and BiOCl electrospun nanosheets and morphology-dependent photocatalytic properties(Royal Society of Chemistry, 2014) Babu, V. J.; Bhavatharini, R. S. R.; Ramakrishna, S.BiOCl and Bi2O3 nanosheet like structures were produced by electrospinning. The morphological changes were observed by changing precursor (BiOCl3 and Bi(NO3)3·5H 2O) concentrations. These nanosheets were analyzed by XRD, which reveals that the crystal structures of BiOCl and Bi2O3 belonged to tetragonal and beta-phase systems respectively. Both nanostructures were employed for the photodegradation of Alizarin Red S (ARS) dye under UV light (<390 nm) irradiation. BiOCl nanosheet like structures exhibited superior photocatalytic activity (PCA) for the degradation of ARS dye and their half-life was estimated from the kinetic plots of PCA. A plausible reaction mechanism is proposed for the PCA and discussed in detail. © the Partner Organisations 2014.Item Open Access Cyclodextrin functionalized poly(methyl methacrylate) (PMMA) electrospun nanofibers for organic vapors waste treatment(Elsevier BV, 2010) Uyar, Tamer; Havelund, R.; Nur, Y.; Balan, A.; Hacaloglu, J.; Toppare, L.; Besenbacher, F.; Kingshott, P.Poly(methyl methacrylate) (PMMA) nanofibers containing the inclusion complex forming betacyclodextrin (_-CD) were successfully produced by means of electrospinning in order to develop functional nanofibrous webs for organic vapor waste treatment. Electrospinning of uniform PMMA nanofibers containing different loadings of _-CD (10%, 25% and 50% (w/w)) was achieved. The surface sensitive spectroscopic techniques; X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) showed that some of the _-CD molecules are present on the surface of the PMMA nanofibers, which is essential for the trapping of organic vapors by inclusion complexation. Direct pyrolysis mass spectrometry (DP-MS) studies showed that PMMA nanowebs containing _-CD can entrap organic vapors such as aniline, styrene and toluene from the surroundings due to inclusion complexation with _-CD that is present on the fiber surface. Our study showed that electrospun nanowebs functionalized with cyclodextrinsmayhave the potential to be used as molecular filters and/or nanofilters for the treatment of organic vapor waste and air filtration purposes.Item Open Access Electrospun nanowebs incorporating essential oil/cyclodextrin inclusion complexes(Fiber Society, 2012) Kayaci, F.; Ertas, Y.; Uyar, T.In this study, we aimed to produce functional polyvinyl alcohol (PVA) electrospun nanowebs containing essential oil; eugenol (EG), that have long-term durability and high temperature stability due to cyclodextrin (CD) inclusion complexation.Item Open Access Electrospun polymeric nanofibrous composites containing TiO2 short nanofibers(2011) Deniz, A. E.; Celebioglu A.; Kayaci, F.; Uyar, TamerIn this study, polymeric nanofibrous composites containing anatase TiO 2 short nanofibers (TiO2-SNF) were successfully produced via electrospinning. The fabrication of the nanofibrous composite structure includes two steps. First, anatase TiO2 nanofibers were obtained by calcination of electrospun PVP/TiO2 nanofibers and then crushed into short nanofibers ranging from few microns in length. Second, these TiO 2-SNF were dispersed into polymer solutions and then electrospun into nanofibrous composites. We obtained nanofibers containing TiO2-SNF from different polymer types including PMMA, PAN, PET and PC. The SEM and TEM imaging indicated that some of the TiO2-SNF were fully covered by the polymeric matrix whereas some TiO2-SNF were partially covered and/or stick on the surface of the fibers. The photocatalytic activity of nanofibrous composites containing TiO2-SNF was evaluated by monitoring the photocatalytic decomposition of a model dye (rhodamine-6G) under UV irradiation. © 2011 Elsevier B.V. All rights reserved.Item Open Access Encapsulation of vanillin/cyclodextrin inclusion complex in electrospun polyvinyl alcohol (PVA) nanowebs: prolonged shelf-life and high temperature stability of vanillin(2012-08) Kayaci, F.; Uyar, TamerWe produced functional nanowebs, containing vanillin, having prolonged shelf-life and high temperature stability facilitated by cyclodextrin (CD) inclusion complexation. Polyvinyl alcohol (PVA) nanowebs incorporating vanillin/cyclodextrin inclusion complex (vanillin/CD-IC) were produced via electrospinning technique. The vanillin/CD-IC was prepared with three types of CDs; α-CD, β-CD and γ-CD to find out the most favourable CD type for the stabilization of vanillin. PVA/vanillin/CD-IC nanofibres, having fibre diameters around ∼200 nm, were successfully electrospun from aqueous mixture of PVA and vanillin/CD-IC. Our results indicated that vanillin with enhanced durability and high temperature stability was achieved for PVA/vanillin/CD-IC nanowebs due to complexation of vanillin with CD, whereas the PVA nanofibres without CD-IC could not effectively preserve the vanillin. Additionally, we observed that PVA/vanillin/γ-CD-IC nanoweb was more effective for the stabilization and slow release of vanillin suggesting that the strength of interaction between vanillin and the γ-CD cavity is stronger when compared to α-CD and β-CD. © 2012 Elsevier Ltd. All rights reserved.Item Open Access Evaluation of fiber diameter and morphology differences for electrospun fibers on bacterial immobilization and bioremediation performance(Elsevier, 2017-05) Sarioglu O.F.; Celebioglu A.; Tekinay, T.; Uyar, TamerIn this report, morphology and fiber diameter differences of electrospun polysulfone (PSU) fibers on bacterial immobilization and bioremediation performance were evaluated. PSU fibers were produced with aligned or randomly oriented morphologies, and PSU fibers with thinner and thicker diameters were also produced. PSU fibers were utilized as carrier matrices for bacterial integration and the sample showing highest bacterial immobilization was tested for bioremediation of ammonium and methylene blue dye in water. It was found that randomly oriented and thinner PSU fibers are the optimal system for bacterial immobilization, hence bioremediation studies were performed with this sample. The results demonstrated that bacteria immobilized PSU fibers are promising candidates for simultaneous removal of ammonium and methylene blue dye, and they have a potential to be used in remediation of water systems.Item Open Access Flexible organic-inorganic core-shell nanofibers by electrospinning and atomic layer deposition(CRC Press, 2012) Kayacı, Fatma; Çağla, Özgit-Akgün; Dönmez, İnci; Bıyıklı, Necmi; Uyar, TamerOrganic-inorganic core-shell nanofibers were fabricated by combining electrospinning and atomic layer deposition (ALD). In the first step, nylon66 (polymeric organic core) nanofibers having different average fiber diameters (∼100 nm, ∼250 nm and ∼650 nm) were electrospun by using different solvent systems and polymer concentrations. In the second step, uniform and conformal layer of zinc oxide (ZnO) (inorganic shell) with precise thickness (∼90 nm) and composition on the round surface of the nylon nanofibers were deposited by ALD. The core-shell nylon66-ZnO nanofibers have shown unique properties such as structural flexibility due to the polymeric core and photocatalytic activity due to the ZnO shell layer.Item Open Access Functional electrospun polystyrene nanofibers incorporating α-, β-, and γ-cyclodextrins: Comparison of molecular filter performance(2010) Uyar, Tamer; Havelund, R.; Hacaloglu, J.; Besenbacher, F.; Kingshott, P.Electrospinning has been used to successfully create polystyrene (PS) nanofibers containing either of three different types of cyclodextrin (CD); α-CD, β-CD, and γ-CD. These three CDs are chosen because they have different sized cavities that potentially allow for selective inclusion complex (IC) formation with molecules of different size or differences in affinity of IC formation with one type of molecule. The CD containing electrospun PS nanofibers (PS/CD) were initially characterized by scanning electron microscopy (SEM) to determine the uniformity of the fibers and their fiber diameter distributions. X-ray photoelectron spectroscopy (XPS) was used to quantitatively determine the concentration of each CD on the different fiber surfaces. Static time-of-flight secondary ion mass spectrometry (static-ToF-SIMS) showed the presence of each type of CD on the PS nanofibers by the detection of both the CD sodium adduct molecular ions (M + Na+) and lower molecular weight oxygen containing fragment ions. The comparative efficiency of the PS/CD nanofibers/nanoweb for removing phenolphthalein, a model organic compound, from solution was determined by UV-vis spectrometry, and the kinetics of phenolphthalein capture was shown to follow the trend PS/α-CD > PS/β-CD > PS/γ-CD. Direct pyrolysis mass spectrometry (DP-MS) was also performed to ascertain the relative binding strengths of the phenolphthalein for the CD cavities, and the results showed the trend in the interaction strength was β-CD > γ-CD > α-CD. Our results demonstrate that nanofibers produced by electrospinning that incorporate cyclodextrins with different sized cavities can indeed filter organic molecules and can potentially be used for filtration, purification, and/or separation processes. © 2010 American Chemical Society.Item Open Access Preparation of Al 2O 3and AlN nanotubes by atomic layer deposition(Cambridge University Press, 2012) Ozgit-Akgun, Çagla; Kayacı, Fatma; Dönmez, İnci; Çağatay, Engin; Uyar, Tamer; Bıyıklı, NecmiAl 2O 3 and AlN nanotubes were fabricated by depositing conformal thin films via atomic layer deposition (ALD) on electrospun nylon 66 (PA66) nanofiber templates. Depositions were carried out at 200°C, using trimethylaluminum (TMAl), water (H 2O), and ammonia (NH 3) as the aluminum, oxygen, and nitrogen precursors, respectively. Deposition rates of Al 2O 3 and AlN at this temperature were ∼1.05 and 0.86 Å/cycle. After the depositions, Al 2O 3- and AlN-coated nanofibers were calcinated at 500°C for 2 h in order to remove organic components. Nanotubes were characterized by using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). AlN nanotubes were polycrystalline as determined by high resolution TEM (HR-TEM) and selected area electron diffraction (SAED). TEM images of all the samples reported in this study indicated uniform wall thicknesses. © 2012 Materials Research Society.Item Open Access Water-soluble non-polymeric electrospun cyclodextrin nanofiber template for the synthesis of metal oxide tubes by atomic layer deposition(Royal Society of Chemistry, 2014) Celebioglu A.; Vempati S.; Ozgit Akgun, C.; Bıyıklı, Necmi; Uyar, TamerWe report on the suitability of water-soluble non-polymeric electrospun cyclodextrin (CD) nanofiber templates by using atomic layer deposition (ALD) to yield metal oxide tubes. To demonstrate this, water-soluble electrospun CD nanofibers were chosen as template to produce metal oxide tubes where we have tested two examples of ALD coatings, namely, Al2O3 and ZnO. After the ALD coating on the CD nanofibers, the CD core is simply dissolved in water to yield metal oxide tubes. Morphological investigations suggested that Al2O3 is smoother in contrast to ZnO which shows a grainy structure. Structural characterization evidenced amorphous Al2O3 and highly crystalline ZnO. Given the applicability of Al2O3 and ZnO in various contexts the ionic states of Al, Zn and O are also investigated. After the washing step to remove the CD core, Al2O3 developed some hydroxylation, while ZnO hosts various oxygen related functional groups.