Chemistry / Kimya

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

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2006 - 200912020 - 20211

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Subject: search.filters.subject.Nanostructured materialsWoS Q: search.filters.wosQuartile.Q2

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Now showing 1 - 2 of 2
  • Article
    Citation - WoS: 15
    Citation - Scopus: 14
    Electroactive Nanogel Formation by Reactive Layer-By Assembly of Polyester and Branched Polyethylenimine Via Aza-Michael Addition
    (American Chemical Society, 2021) Yıldırımkaraman, Öykü; Özenler, Sezer; Günay, Ufuk Saim; Durmaz, Hakan; Yıldız, Ümit Hakan
    We here demonstrate the utilization of reactive layer-by-layer (rLBL) assembly to form a nanogel coating made of branched polyethylenimine (BPEI) and alkyne containing polyester (PE) on a gold surface. The rLBL is generated by the rapid aza-Michael addition reaction of the alkyne group of PE and the -NH2 groups of BPEI by yielding a homogeneous gel coating on the gold substrate. The thickness profile of the nanogel revealed that a 400 nm thick coating is formed by six multilayers of rLBL, and it exhibits 50 nm roughness over 8 mu m distance. The LBL characteristics were determined via depth profiling analysis by X-ray photoelectron spectroscopy, and it has been shown that a 70-100 nm periodic increase in gel thickness is a consequence of consecutive cycles of rLBL. A detailed XPS analysis was performed to determine the yield of the rLBL reaction: the average yield was deduced as 86.4% by the ratio of the binding energies at 286.26 eV, (C CN-C bond) and 283.33 eV, (C C triple bond). The electrochemical characterization of the nanogels ascertains that up to the six-multilayered rLBL of BPEI-PE is electroactive, and the nanogel permeability had led to drive mass and charge transfer effectively. These results promise that nanogel formation by rLBL films may be a straightforward modification of electrodes approach, and it exhibits potential for the application of soft biointerfaces.
  • 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.