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Subject: Coatings × WGL Institute: IPHT ×

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    Large-area wet-chemical deposition of nanoporous tungstic silica coatings
    (London [u.a.] : RSC, 2015) Nielsen, K.H.; Wondraczek, K.; Schubert, U.S.; Wondraczek, L.
    We report on a facile procedure for synthesis of nanoporous coatings of tungstic silica through wet-chemical deposition and post-treatment of tungsten-doped potassium silicate solutions. The process relies on an aqueous washing and ion exchange step where dispersed potassium salt deposits are removed from a 150 nm silicate gel layer. Through an adjustment of the pH value of the washing agent within the solubility regime of a tungstic salt precursor, the tungsten content of the remaining nanostructured coating can be controlled. We propose this route as a universal approach for the deposition of large-area coatings of nanoporous silica with the potential for incorporating a broad variety of other dopant species. As for the present case, we observe, on the one hand, antireflective properties which enable the reduction of reflection losses from float glass by up to 3.7 percent points. On the other hand, the incorporation of nanoscale tungstic precipitates provides a lever for tailoring the coating hydrophilicity and, eventually, also surface acidity. This may provide a future route for combining optical performance with anti-fouling functionality.
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    SPION@polydehydroalanine hybrid particles
    (London : RSC Publishing, 2015) von der Lühe, Moritz; Günther, Ulrike; Weidner, Andreas; Gräfe, Christine; Clement, Joachim H.; Dutz, Silvio; Schacher, Felix H.
    It is generally accepted that a protein corona is rapidly formed upon exposure of nanoparticles to biological fluids and that both the amount and the composition of adsorbed proteins affect the dispersion properties of the resulting particles. Hereby, the net charge and overall charge density of the pristine nanoparticles are supposed to play a crucial role. In an attempt to control both charge and charge distribution, we report on the coating of superparamagnetic iron oxide nanoparticles (SPIONs) with different polyelectrolytes. Starting from orthogonally protected polydehydroalanine, the material can be easily transformed into a polyanion (poly(tert-butoxycarbonyl acrylic acid), PtBAA), polycation (poly(aminomethylacrylate), PAMA), or even a polyzwitterion (polydehydroalanine, PDha). While coating of SPIONs with PtBAA and PDha was shown to be successful, approaches using PAMA have failed so far. The dispersion properties of the resulting hybrid particles have been investigated using dynamic light scattering (DLS), zeta-potential, and TEM measurements – the amount of adsorbed polymer was quantified using vibrating sample magnetometry (VSM) and thermogravimetric analysis (TGA).