Browsing by Author "Demir, Mine"

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Open Access
A sustainable preparation of catalytically active and antibacterial cellulose metal nanocomposites via ball milling of cellulose
(Royal Society of Chemistry, 2020-01) Kwiczak-Yiğitbaşı, Joanna; Laçin, Özge; Demir, Mine; Ahan, Recep Erdem; Şeker, Urartu Özgür Şafak; Baytekin, Bilge
Cellulose, the most abundant polymer on Earth, and its composites have recently gained importance for the production of sustainable materials. These materials should be produced using green methods that avoid the utilization of toxic chemicals to ensure integrity for environmental sustainability. Ball milling, which gives a straightforward and (often) green synthetic access to materials, can be used to achieve this goal. Previously, it was shown that mechanochemical bond breakages in polymers generate mechanoradicals, which can be used to drive further reactions and to form polymer composites. In this study, we show that cellulose mechanoradicals generated during the ball milling of cellulose can reduce various metal ions to the corresponding metal nanoparticles (NPs) (Au, Ag, Pt, Pd, Co, and Cu), which are deposited and stabilized in the cellulose matrix. Using mechanoradicals to reduce the metal ions and form the cellulose composites, (1) the number of synthetic steps is reduced, and (2) the conventionally used, toxic reducing and stabilizing agents are avoided, which also prevents the contamination of the composites. The cellulose–metal nanoparticle composites can exhibit a wide range of properties that depend on the metal nanoparticle in the composite; e.g., Au–cellulose nanocomposites exhibit catalytic activity, and Ag–cellulose nanocomposites exhibit antibacterial properties. The ball-milling method also permits blend formation using synthetic polymers, which allows tuning the physical properties of the final material. Finally, the method shown here provides a quick access to versatile metal nanoparticle cellulose composites (and their blends), which may find applications, such as in paper-based diagnostics and catalysis.
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Türk Nümismatik Derneği ve Türkiye'de para koleksiyonculuğu tarihi
(Bilkent University, 2018) Demirkaya, Zülal Beyza; Demir, Mine; Başar, Gizem; Bağış, Yağmur; Erükçü, Bora
Open Access
Ultrasonication for environmentally friendly preparation of antimicrobial and catalytically active nanocomposites of cellulosic textiles
(American Chemical Society, 2020) Kwiczak-Yiǧitbaşı, Joanna; Demir, Mine; Ahan, Recep Erdem; Canlı, S.; Şafak Şeker, Urartu Özgür; Baytekin, Bilge
The global demand for sustainable and functional fibers and textile materials is increasing with the pressure to limit the synthetic petroleum-based counterparts. In this study, we use ultrasonication for the preparation of eco-friendly cellulose fabrics bearing silver or gold nanoparticles (NPs). The mechanochemistry of cellulose is based on the breakage of glycosidic bonds and the formation of mechanoradicals. These mechanoradicals can reduce Au3+ and Ag+ ions in solution, and the reduced metals can be stabilized by the cellulose chains as nanoparticles. Here, we formed the mechanoradicals in the fabrics by sonication (on the order of 1018 per gram), which is confirmed by ESR. The sizes and the metallic nature of NPs and the structural and morphological changes in the fabrics upon ultrasonication were studied by SEM, XPS, FTIR-ATR, XRD, and TEM. The displayed preparation method is shown to yield antibacterial AgNP-fabric and catalytically active AuNP-fabric composites, with up to a 14% yield of metal ion reduction. Since the method involves only the sonication of the fabric in aqueous solutions, and uses no hazardous reducing and stabilizing agents, it provides quick and environment-friendly access to fabric nanocomposites, which have applications in medical textiles, catalysis, and materials for energy.