Chemistry / Kimya

Permanent URI for this collectionhttps://hdl.handle.net/11147/4072

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Publisher: search.filters.publisher.John Wiley and Sons Inc.Subject: search.filters.subject.Nanoparticles

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Now showing 1 - 3 of 3
  • Article
    Citation - WoS: 47
    Citation - Scopus: 49
    Simultaneous Identification of Spectral Properties and Sizes of Multiple Particles in Solution With Subnanometer Resolution
    (John Wiley and Sons Inc., 2016) Karabudak, Engin; Karabudak, Engin; Brookes, Emre; Lesnyak, Vladimir; Gaponik, Nikolai; Eychmüller, Alexander; Walter, Johannes; Segets, Doris; Peukert, Wolfgang; Wohlleben, Wendel; Demeler, Borries; Cölfen, Helmut; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of Technology
    We report an unsurpassed solution characterization technique based on analytical ultracentrifugation, which demonstrates exceptional potential for resolving particle sizes in solution with sub-nm resolution. We achieve this improvement in resolution by simultaneously measuring UV/Vis spectra while hydrodynamically separating individual components in the mixture. By equipping an analytical ultracentrifuge with a novel multi-wavelength detector, we are adding a new spectral discovery dimension to traditional hydrodynamic characterization, and amplify the information obtained by orders of magnitude. We demonstrate the power of this technique by characterizing unpurified CdTe nanoparticle samples, avoiding tedious and often impossible purification and fractionation of nanoparticles into apparently monodisperse fractions. With this approach, we have for the first time identified the pure spectral properties and band-gap positions of discrete species present in the CdTe mixture.
  • Article
    Citation - WoS: 30
    Citation - Scopus: 30
    Glycidyl-Methacry Late-Based Electrospun Mats and Catalytic Silver Nanoparticles
    (John Wiley and Sons Inc., 2008) Demir, Mustafa Muammer; Demir, Mustafa Muammer; Uğur, Gökçe; Gülgün, Mehmet A.; Menceloğlu, Yusuf Z.; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    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: 15
    Aggregation of Fillers Blended Into Random Elastomeric Networks: Theory and Comparison With Experiments
    (John Wiley and Sons Inc., 2006) Demir, Mustafa Muammer; Demir, Mustafa Muammer; Erman, Burak; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    A theoretical model describing aggregation of filler particles in amorphous elastomers is proposed. The model is based on a counting technique originally used in genome analysis to characterize the size and distribution of overlapping segments randomly placed on a DNA molecule. In the present model, the particles are first assumed to aggregate randomly upon mixing into the elastomer and then-sizes are calculated. The sizes and distributions of aggregates are also studied in the presence of attractive interparticle forces. Results of the proposed model are compared with experimental data on silica-filled end-linked poly(dimethyl-siloxane) networks. Comparison of the theory and experiment shows that the random aggregation assumption where no attractive forces exist between the particles is not valid and a significant attraction between the silica particles is needed in the theory to justify the experimental data obtained using atomic force microscopy. For filler content below 1.45 vol.-%, the model agrees, qualitatively, with experiment and shows the increase in cluster size with increasing amount of filler. It also explains the increase in the dispersion of aggregate sizes with increasing amount of filler.