Browsing by Author "Ertas, Y."

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    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.
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    Functional polymeric nanofibers via electrospinning
    (2012) Uyar, T.; Kayacı, F.; Celebioglu, A.; Aytac, Z.; Ertas, Y.
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    Main-chain polybenzoxazine nanofibers via electrospinning
    (Elsevier, 2014-01-30) Ertas, Y.; Uyar, Tamer
    Here we report the successful production of nanofibers from main-chain polybenzoxazines (MCPBz) via electrospinning without using any other carrier polymer matrix. Two different types of MCPBz (PBA-ad6 and PBA-ad12) were synthesized by using two types of difunctional amine (1,6-diaminohexane and 1,12-diaminododecane), bisphenol-A, and paraformaldehyde as starting materials through a Mannich reaction. 1H NMR and FTIR spectroscopy studies have confirmed the chemical structures of the two MCPBz. We were able to obtain highly concentrated homogeneous solutions of the two MCPBz in chloroform/N,N-dimethylformamide (DMF) (4:1, v/v) solvent system. The electrospinning conditions were optimized in order to produce bead-free, uniform and continuous nanofibers from these two MCPBz by varying the concentrations of PBA-ad6 (30–45%, w/v) and PBA-ad12 (15–20%, w/v) in chloroform/DMF (4:1, v/v). The bead-free fiber morphology was evidenced under SEM imaging when PBA-ad6 and PBA-ad12 were electrospun at solution concentration of 40% and 18% (w/v), respectively. The nanofibrous mats of MCPBz were obtained as free-standing material, yet, PBA-ad12 mat was more flexible than and PBA-ad6 mat. Furthermore, the curing studies of these MCPBz nanofibrous mats were performed to obtain cross-linked materials.
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    Sensitive surface states and their passivation mechanism in CdS quantum dots
    (American Chemical Society, 2013) Vempati S.; Ertas, Y.; Uyar, Tamer
    We report on phase sensitive surface states of CdS quantum dots (QDs), where it is noticed that a simple phase change from dispersion to solid has shown significant influence on the emission spectrum. As the solvent evaporates from the dispersion, apparently yellow dispersion transforms into a white light emitter because of the conformal changes in the polymer that surrounds the QDs. In turn, these changes catalyze the emission from three specific wavelengths in the blue region of the spectrum, shifting the surface defects closer to the conduction band of CdS. In the phase change from dispersion to solid, flexible and dangling polymer chains are transformed into rigid moieties that can be treated as a modified chemical environment. Furthermore, to ascertain the origin of the new emission lines, we have studied a dipole interaction-based passivation mechanism between QDs and the polymer. The proposed mechanism may be valuable for designing future QD-based fluorophores and explains the sensitivity of the surface states in the case of CdS. © 2013 American Chemical Society.