TY - JOUR A1 - Das, Chayanika A1 - Kastania, Eleni A1 - Witt, Julia A1 - Özcan Sandikcioglu, Özlem T1 - Corrosion protection properties of poly(4-vinyl pyridine) containing multilayer polymeric coatings on magnesium alloy AZ31 JF - Materials and Corrosion N2 - The aim of this study is to develop polymeric thin films for corrosion protection of magnesium alloy AZ31. As polymer matrix, poly(4-vinyl pyridine) (P4VP) is selected due to its semiconducting properties and protonic conductivity. Polyacrylic acid is tested as crosslinking layers to improve interfacial adhesion. The macroscopic corrosion properties of the multilayer coatings are investigated by means of electrochemical methods, such as linear sweep voltammetry and electrochemical impedance spectroscopy (EIS), in corrosive media simulating technical and biomedical applications. It is demonstrated that thin multilayer coatings can suppress the corrosion rates of magnesium alloys. To our best knowledge, this is the first demonstration of the use of P4VP as a conducting polymer film with protonic conductivity for corrosion protection of magnesium alloys. KW - Multilayercoatings KW - AZ31 KW - Corrosion protection KW - Intrinsically conducting polymers KW - Magnesium alloys PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-551799 DO - https://doi.org/10.1002/maco.202112708 SN - 0947-5117 VL - 73 IS - 3 SP - 427 EP - 435 PB - Wiley VHC-Verlag AN - OPUS4-55179 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rautenberg, Max A1 - Bhattacharya, Biswajit A1 - Das, Chayanika A1 - Emmerling, Franziska T1 - Mechanochemical Synthesis of Phosphonate-Based Proton Conducting Metal-Organic Frameworks JF - Inorganic Chemistry N2 - Water-stable metal−organic frameworks (MOFs) with proton-conducting behavior have attracted great attention as promising materials for proton-exchange membrane fuel cells. Herein, we report the mechanochemical gram-scale synthesis of three new mixed-ligand phosphonate-based MOFs, {Co(H2PhDPA)(4,4′-bipy)H2O)·2H2O}n (BAM-1), {Fe(H2PhDPA)(4,4′-bipy) (H2O)·2H2O}n (BAM-2), and {Cu(H2PhDPA)(dpe)2(H2O)2·2H2O}n (BAM-3) [where H2PhDPA = phenylene diphosphonate, 4,4′-bipy = 4,4′-bipyridine, and dpe = 1,2-di(4-pyridyl)ethylene]. Single-crystal X-ray diffraction measurements revealed that BAM-1 and BAM-2 are isostructural and possess a three-dimensional (3D) network structure comprising one-dimensional (1D) channels filled with guest water molecules. Instead, BAM-3 displays a 1D network structure extended into a 3D supramolecular structure through hydrogenbonding and π−π interactions. In all three structures, guest water molecules are interconnected with the uncoordinated acidic hydroxyl groups of the phosphonate moieties and coordinated water molecules by means of extended hydrogen-bonding interactions. BAM-1 and BAM-2 showed a gradual increase in proton conductivity with increasing temperature and reached 4.9 × 10−5 and 4.4 × 10−5 S cm−1 at 90 °C and 98% relative humidity (RH). The highest proton conductivity recorded for BAM-3 was 1.4 × 10−5 S cm−1 at 50 °C and 98% RH. Upon further heating, BAM-3 undergoes dehydration followed by a phase transition to another crystalline form which largely affects its performance. All compounds exhibited a proton hopping (Grotthuss model) mechanism, as suggested by their low activation energy. KW - Mechanochemistry KW - Metal-organic-frameworks KW - Proton conductivity PY - 2022 DO - https://doi.org/10.1021/acs.inorgchem.2c01023 VL - 61 SP - 10801 EP - 10809 PB - ACS Publications AN - OPUS4-55448 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Das, Chayanika A1 - Witt, Julia A1 - Kastanias, Eleni A1 - Özcan Sandikcioglu, Özlem T1 - Graphene-polymer nanocomposite coatings for corrosion protection of Mg-alloys N2 - Mg is a very promising material for lightweight construction and biomedical applications. However, the applicability of Mg and its alloys is hindered by its high corrosion susceptibility. Moreover, due to the toxicity of most inorganic conversion coating systems, the development of novel pre-treatment strategies for technical alloys are of vital importance. The aim of this study is to develop polymeric bilayer thin films for corrosion protection of Mg-alloys. As polymer matrix, poly(4-vinyl pyridine) (P4VP) was selected due to its semiconducting properties and protonic conductivity. In contrast to ICPs with electronic conductivity, the pH-dependant, reversible protonation/de-protonation capability of the P4VP has been utilized to synthesize environment-responsive coatings. Polyacrylicacid (PAA) was tested as crosslinking layers to improve interfacial interactions between the polymeric layers. The macroscopic corrosion properties of the bilayer coatings were investigated by means of electrochemical methods such as linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) in corrosive media simulating technical and biomedical applications. The presentation summarizes our recent results on the synthesis and characterization of this novel coating system with a special focus on their interfacial stability and corrosion protection properties. T2 - E-MRS 2019 Spring Meeting CY - Nice, France DA - 27.05.2019 KW - Polymer bilayer coatings KW - Graphene polymer nanocomposite KW - Corrosion inhibition KW - Magnesium alloy PY - 2019 AN - OPUS4-49848 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Das, Chayanika A1 - Witt, Julia A1 - Kastanias, Eleni A1 - Özcan Sandikcioglu, Özlem T1 - Graphene polymer nanocomposite coatings for corrosion inhibition of mg alloys N2 - Mg is a very promising material for lightweight construction and biomedical applications. However, the applicability of Mg and its alloys is hindered by its high corrosion susceptibility. Moreover, due to the toxicity of most inorganic conversion coating systems, the development of novel pre-treatment strategies for technical alloys are of vital importance. Recently, the application of intrinsically conducting polymers (ICPs) have been introduced as an alternative approach for corrosion protection of Mg alloys. ICPs with electronic conductivity are known to be able to passivate small defects, however they fail in the presence of large defects due to fast coating reduction and increased cation transport if macroscopically extended percolation networks exist. The aim of this study is to develop graphene-polymer nanocomposite thin films for corrosion protection of Mg-alloys. As polymer matrix, poly(4-vinyl pyridine) (P4VP) was selected due to its semiconducting properties and protonic conductivity. In contrast to ICPs with electronic conductivity, the pH-dependant, reversible protonation/de-protonation capability of the P4VP has been utilized to synthesize environment-responsive coatings. The presentation summarizes our recent results on the synthesis and characterization of this novel coating system with a special focus on their interfacial stability and corrosion protection properties. T2 - Eurocorr 2019 CY - Seville, Spain DA - 09.09.2019 KW - Polymer bilayer coatings KW - Ggraphene polymer nanocomposite KW - Corrosion inhibition KW - Magnesium alloy PY - 2019 AN - OPUS4-49849 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rautenberg, Max A1 - Akhmetova, Irina A1 - Das, Chayanika A1 - Bhattacharya, Biswajit A1 - Emmerling, Franziska T1 - Synthesis and In Situ Monitoring of Mechanochemical Preparation of Highly Proton Conductive Hydrogen-Bonded Metal Phosphonates JF - ACS Omega N2 - Crystalline porous materials are recognized as promising proton conductors for the proton exchange membrane (PEM) in fuel cell technology owing to their tunable framework structure. However, it is still a challenging bulk synthesis for real-world applications of these materials. Herein, we report the mechanochemical gram-scale synthesis of two isostructural metal hydrogen-bonded organic frameworks (MHOFs) of Co(II) and Ni(II) based on 1-hydroxyethylidenediphosphonic acid (HEDPH4) with 2,2′-bipyridine (2,2′-bipy): Co(HEDPH3)2(2,2′-bipy)·H2O (1) and Ni(HEDPH3)2(2,2′-bipy)·H2O (2). In situ monitoring of the mechanochemical synthesis using different synchrotron-based techniques revealed a one-step mechanism – the starting materials are directly converted to the product. With the existence of extensive hydrogen bonds with amphiprotic uncoordinated phosphonate hydroxyl and oxygen atoms, both frameworks exhibited proton conduction in the range of 10–4 S cm–1 at room temperature under humid conditions. This study demonstrates the potential of green mechanosynthesis for bulk material preparation of framework-based solid-state proton conductors. KW - Mechanochemistry KW - Proton conductivity KW - Metal Organic Frameworks PY - 2023 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-577777 DO - https://doi.org/10.1021/acssuschemeng.2c07509 VL - 8 IS - 19 SP - 16687 EP - 16693 PB - ACS Publications AN - OPUS4-57777 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -