Materials Science and Engineering / Malzeme Bilimi ve Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4719
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Article Citation - WoS: 11Citation - Scopus: 13Effect of Cnt Incorporation on Pan/Ppy Nanofibers Synthesized by Electrospinning Method(TÜBİTAK, 2020) İnce Yardımcı, Atike; Selamet, Yusuf; Tanoğlu, Metin; Tanoğlu, Metin; Yılmaz, Selahattin; Yılmaz, Selahattin; Selamet, Yusuf; 03.02. Department of Chemical Engineering; 03.10. Department of Mechanical Engineering; 04.05. Department of Pyhsics; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of TechnologyIn this study, carbon nanotubes (CNTs) added polyacrylonitrile/polypyrrole (PAN/PPy) electrospun nanofibers were produced. Average diameters of the nanofibers were measured as 268 and 153 nm for 10 and 25 wt% of PPy contents, respectively. A relatively higher strain to failure values (23.3%) were observed for the low PPy content. When as-grown CNTs (1 and 4 wt%) were added into the PAN/PPy blends, disordered nanofibers were observed to form within the microstructure. To improve the interfacial properties of CNTs/PAN/PPy composites, CNTs were functionalized with H2SO4/HNO3/HCl solution. The functionalized CNTs were well dispersed within the nanofibers and aligned along the direction of nanofibers. Therefore, beads formation on nanofibers decreased. The impedance of the nanofibers was found to decrease with the PPy content and CNT addition. These nanofibers had a great potential to be used as an electrochemical actuator or a tissue engineering scaffold.Article Citation - WoS: 25Citation - Scopus: 27Osteogenic Differentiation of Mesenchymal Stem Cells on Random and Aligned Pan/Ppy Nanofibrous Scaffolds(SAGE Publications, 2019) Meşe Özçivici, Gülistan; Selamet, Yusuf; Baskan, Öznur; Özçivici, Engin; Yılmaz, Selahattin; Özçivici, Engin; 03.01. Department of Bioengineering; 03.02. Department of Chemical Engineering; 01. Izmir Institute of Technology; 04.03. Department of Molecular Biology and Genetics; 04.05. Department of Pyhsics; 03. Faculty of Engineering; 04. Faculty of ScienceThe aim of this study was to develop random and aligned polyacrilonitrile (PAN)/polypyrrole (PPy) nanofibrous scaffolds by electrospinning technique for osteogenic differentiation of mesenchymal stem cells. Nanofibers were fabricated successfully as straight, smooth, and free from bead formation. The average diameter of random and aligned nanofibers was 268(+/- 49) nm and 225(+/- 72) nm, respectively. Alignment process increased the tensile strength of nanofibers 3.9-fold, while the tensile strain of nanofibers decreased by 78%. PAN/PPy nanofibers were hydrophilic with the contact angle value of about 32 degrees and alignment did not affect the contact angle value. Random and aligned PAN/PPy nanofibers were investigated as a scaffold material for osteogenic differentiation of D1 ORL UVA mouse bone marrow mesenchymal stem cells. Cells were able to attach and grow on nanofibers confirmed by cell viability results. Stem cells that were cultured with osteogenic induction were able to mineralize on electrospun nanofibers based on alizarin red and Von Kossa dye staining. For aligned PPy nanofibers, mineralization occurred in the fiber alignment direction. Consequently, PAN/PPy nanofibrous mats in both random and aligned forms would be potential candidates for bone tissue engineering.Article Citation - WoS: 63Citation - Scopus: 65Amidoxime Functionalized Polymers of Intrinsic Microporosity (pim-1) Electrospun Ultrafine Fibers for Rapid Removal of Uranyl Ions From Water(Elsevier Ltd., 2019) Satılmış, Bekir; Isık, Tuğba; Demir, Mustafa Muammer; Isık, Tuğba; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe Polymers of Intrinsic Microporosity (PIM-1) is considered as one of the most promising polymer candidates for adsorption applications owing to its high surface area and the ability to tailor the functionality for the targeted species. This study reports a facile method for the preparation of amidoxime functionalized PIM-1 fibrous membrane (AF-PIM-FM) by electrospinning technique and its practical use for the extraction of U(VI) ions from aqueous systems via column sorption under continuous flow. Fibrous membrane form of amidoxime functionalized PIM-1 (AF-PIM-FM) was prepared by electrospinning method owing to its excellent processability in dimethylformamide. Bead-free and uniform fibers were obtained as confirmed by SEM imaging and average fiber diameter was 1.69 +/- 0.34 mu m for AF-PIM-FM. In addition, electrospun PIM-1 fibrous membrane (PIM-FM) was prepared as a control group. Structural and thermal characterization of powder and membrane forms of the materials were performed using FT-IR, H-1 NMR, XPS, Elemental analyses, TGA, and DSC. The porosity of the samples was measured by N-2 sorption isotherms confirming amidoxime PIM-1 still maintain their porosity after functionalization. Amidoxime functionality along with membrane structure makes AF-PIM-FM a promising material for uranyl adsorption. First, a comparison between powder and membrane form of amidoxime functionalized PIM-1 was investigated using batch adsorption process. Although membrane form has shown slightly lower adsorption performance in the batch adsorption process, the advantage of using the membrane in column adsorption processes makes membrane form more feasible for real applications. In addition, amidoxime modification enhanced the uranium adsorption ability of PIM-FM up to 20 times. The effect of initial concentration and pH were investigated along with regeneration of the adsorbents. AF-PIM-FM was successfully used for five adsorption-desorption cycles without having any damage on the fibrous structure.Conference Object Citation - WoS: 2Citation - Scopus: 4Monitoring Excimer Formation of Perylene Dye Molecules Within Pmma-Based Nanofiber Via Flim Method(SPIE, 2016) İnci, Mehmet Naci; Demir, Mustafa Muammer; Demir, Mustafa Muammer; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyConfocal fluorescence lifetime imaging microscopy method is used to obtain individual fluorescence intensity and lifetime values of aromatic Perylene dye molecules encapsulated into PMMA based nanofibers. Fluorescence spectrum of aromatic hydrocarbon dye molecules, like perylene, depends on the concentration of dye molecules and these dye molecules display an excimeric emission band besides monomeric emission bands. Due to the dimension of a nanofiber is comparable to the monomer emission wavelength, the presence of nanofibers does not become effective on the decay rates of a single perylene molecule and its lifetime remains unchanged. When the concentration of perylene increases, molecular motion of the perylene molecule is restricted within nanofibers so that excimer emission arises from the partially overlapped conformation. As compared to free excimer emission of perylene, time-resolved experiments show that the fluorescence lifetime of excimer emission of perylene, which is encapsulated into NFs, gets shortened dramatically. Such a decrease in the lifetime is measured to be almost 50 percent, which indicates that the excimer emission of perylene molecules is more sensitive to change in the surrounding environment due to its longer wavelength. Fluorescence lifetime measurements are typically used to confirm the presence of excimers and to construct an excimer formation map of these dye molecules.Article Citation - WoS: 12Citation - Scopus: 11Controlled Surface Mineralization of Metal Oxides on Nanofibers†(Royal Society of Chemistry, 2015) Horzum Polat, Nesrin; Demir, Mustafa Muammer; Mari, Margherita; Wagner, Manfred; Fortunato, Giuseppino; Popa, Ana-Maria; Demir, Mustafa Muammer; Landfester, Katharina; Crespy, Daniel; Mu˜noz-Espi, Rafael; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyWe report a versatile approach for the preparation of metal oxide/polymer hybrid nanofibers by in situ formation of metal oxide nanoparticles on surface-functionalized polymer fibers. Poly (styrene-covinylphosphonic acid) fibers were produced by electrospinning and used as supports for the in situ formation of ceria nanocrystals without further thermal treatment. The crystallization of ceria was induced by the addition of an alkaline solution to fibers loaded with the corresponding precursor. The formation of the inorganic material at the fiber surface was investigated by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The extension of the approach to prepare polymer/titania hybrid nanofibers demonstrates its versatility.