Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

Browse

Filters

20062

Settings

Author: search.filters.author.Wegner, GerhardSubject: search.filters.subject.Nanostructured materials

Search Results

Now showing 1 - 2 of 2
  • Article
    Citation - WoS: 185
    Pmma/Zinc Oxide Nanocomposites Prepared by In-Situ Bulk Polymerization
    (John Wiley and Sons Inc., 2006) Demir, Mustafa Muammer; Memesa, Mine; Castignolles, Patrice; Wegner, Gerhard
    Dispersing surface-modified zinc oxide nano-particles (ZnO) in methyl methacrylate (MMA) improves the free radical bulk polymerization process as well as the thermal stability of the formed polymer. Hydroxy groups available on the ZnO surface may induce a degenerative transfer. This suppresses the gel effect, which leads to a better control of the heat evolution during the late stages of polymerization. The formation of chains having vinylidene end groups and head-to-head links is suppressed, which shifts the onset of thermal decomposition to the regime where decomposition occurs by random chain scission.
  • Article
    Citation - WoS: 83
    Precipitation of Monodisperse Zno Nanocrystals Via Acid-Catalyzed Esterification of Zinc Acetate
    (Royal Society of Chemistry, 2006) Demir, Mustafa Muammer; Muñozz-Espí, Rafael; Lieberwirth, Ingo; Wegner, Gerhard
    A wet-chemical method to produce zinc oxide nanocrystals of monodisperse size distribution (diameter range of 20-80 nm) is presented. The synthesis starts from zinc acetate dihydrate which is converted to ZnO in the presence of 1-pentanol in m-xylene at 130 °C. We report for the first time catalysis of this reaction by p-toluene sulfonic acid monohydrate (p-TSA), which allows a shorter reaction time and improves both the reproducibility of the particle size distribution and the crystallinity of the particles. The reaction can be scaled up to give multigram quantities of product per batch. Particles were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and photoluminesence (PL) spectroscopy. Room temperature PL spectra of ZnO prepared without catalyst exhibit a strong and sharp UV emission band at ca. 385 nm and a weak and very broad green-yellow visible emission centered at ca. 550-560 nm. However, for nanoparticles precipitated in the presence of p-TSA, the UV emission is enhanced by a factor of 4, which can be correlated with the improvement of crystal perfection. A particle formation mechanism is discussed.