WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 30Citation - Scopus: 30Glycidyl-Methacry Late-Based Electrospun Mats and Catalytic Silver Nanoparticles(John Wiley and Sons Inc., 2008) Demir, Mustafa Muammer; Uğur, Gökçe; Gülgün, Mehmet A.; Menceloğlu, Yusuf Z.P(AN-GMA) and PGMA fibers coated with monodisperse silver nanoparticles have been prepared by a combination of electrospinning and electroless plating. The morphology of the electrospun fibers remains unchanged after surface hydrazination. Oxidation of hydrazine in an ammoniacal solution of AgNO 3 reduces and deposits silver atoms along the fiber surface, which then coalesce to Ag particles. The size of the silver nanoparticles is varied between 20-60 nm. Since the density of the active sites for silver reduction is lower in P(AN-GMA), a smaller particle size could be obtained. The catalytic activity of the silver nanoparticles has been confirmed.Article Citation - WoS: 109Citation - Scopus: 119Synthesis of Amidoximated Polyacrylonitrile Fibers and Its Application for Sorption of Aqueous Uranyl Ions Under Continuous Flow(Elsevier Ltd., 2012) Horzum Polat, Nesrin; Shahwan, Talal; Parlak, Onur; Demir, Mustafa MuammerThis study reports a feasible method for the removal of radioactive U(VI) ions from aqueous systems via column sorption under continuous flow. Electrospun polyacrylonitrile (PAN) fibers were used as sorbent materials in a homemade minicolumn. The nitrile groups on the fibers' surface were modified to amidoxime groups using hydroxylamine hydrochloride. Surface modification was observed to enhance the sorption capacity of PAN fibers toward uranium ions by more than 4-fold by virtue of the chelating ability of the amidoxime groups. The experiments investigated the effect of pH, initial concentration, and repetitive loading on the sorption properties of amidoximated PAN fibers. Based on the overall results, the surface-modified fibers seem to be a suitable potential sorbent material for applications in environmental cleanup, particularly for nuclear plants.Article Citation - WoS: 6Citation - Scopus: 6Hierarchial Coassembly of a Cyanine Dye in Poly(vinyl Alcohol) Fibrous Films by Electrospinning(American Chemical Society, 2013) Demir, Mustafa Muammer; Horzum, Nesrin; Özen, Bengisu; Özçelik, SerdarWe report molecular aggregate formation of TTBC (1,1′,3,3′- tetraethyl-5,5′,6,6′-tetrachlorobenzimidazolocarbocyanine) in submicrometer-sized PVA (poly(vinyl alcohol)) fibers by electrospinning. The formation of the molecular aggregate is examined by solution and instrumental parameters of electrospinning. The precursor solution of PVA/TTBC, in the range of 0.016-0.065 wt % is subjected to electrospinning under an electrical field ranging from 0.95 to 1.81 kV cm-1. Both randomly deposited and uniaxially aligned fibers are achieved by using two parallel-positioned metal strips as counter electrode. Photoluminescence and polarized Fourier transform infrared spectroscopies are employed to determine spectral properties of the fibers. H-aggregates are formed within the electrospun fibers, regardless of their alignment, and H- and J-type aggregates coexist in the alternative spin-coated and the cast films. A strongly polarized photoluminescence emission is observed in the direction of uniaxially aligned fibers as a result of the orientation of the H-aggregates along the fiber axis. We demonstrate that electrospinning is a process capable of forming and orienting TTBC aggregates during the structural development of the polymer/dye nanofibers. These fibrous films may potentially find applications in optics and electronics.Article Citation - WoS: 28Citation - Scopus: 29Formation of Pseudoisocyanine J-Aggregates in Poly(vinyl Alcohol) Fibers by Electrospinning(American Chemical Society, 2009) Demir, Mustafa Muammer; Özen, Bengisu; Özçelik, SerdarSubmicrometer diameter, light emitting fibers of poly(vinyl alcohol) (PVA) doped with pseudoisocyanine (1,1′-diethyl-2,2′-cyanine bromide, PIC) dye were prepared by electrospinning. A horizontal setup was employed with a stationary collector consisting of two parallel-positioned metal strips separated by a void gap. Formation of uniaxially aligned and randomly deposited fibers in electrospun films was confirmed by microscopy. Photoluminescence (PL) spectroscopy is used to evaluate spectral properties of both types of fibers doped with PIC. While PIC molecules were individually dispersed in PVA solution, they assemble into J-aggregates upon electrospinning when the weight fraction of PIC molecules is above 2.5 wt %. The formation of J-aggregates was observed in both randomly deposited and uniaxially aligned electrospun fibers. Moreover, the fibers aligned uniaxially showed a high degree of polarized emission (PL |/PL⊥)10), arising from the orientation of J-aggregates along the fiber axis. On the other hand, isotropic emission of J-aggregates was observed from the fibers deposited randomly. As a conclusion, electrospinning was found to be an efficient and a practical method to form highly oriented J-aggregates dispersed into polymer fibers. To the best of our knowledge, it is the first time formation of J-aggregates (a bottom-up approach) and electrospinning (a topdown approach) is successfully combined.