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End date: 2019 × Start date: 2010 × DDC: 620 × Publisher: Basel : MDPI × search.filters.applied.f.series: Polymers 11 (2019), Nr. 11 ×

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    Shape-Memory Metallopolymer Networks Based on a Triazole–Pyridine Ligand
    (Basel : MDPI, 2019) Meurer, Josefine; Hniopek, Julian; Zechel, Stefan; Enke, Marcel; Vitz, Jürgen; Schmitt, Michael; Popp, Jürgen; Hager, Martin D.; Schubert, Ulrich S.
    Shape memory polymers represent an interesting class of stimuli-responsive polymers. With their ability to memorize and recover their original shape, they could be useful in almost every area of our daily life. We herein present the synthesis of shape-memory metallopolymers in which the switching unit is designed by using bis(pyridine–triazole) metal complexes. The polymer networks were synthesized via free radical polymerization of methyl-, ethyl- or butyl-methacrylate, tri(ethylene glycol) dimethacrylate and a methacrylate moiety of the triazole–pyridine ligand. By the addition of zinc(II) or cobalt(II) acetate it was possible to achieve metallopolymer networks featuring shape-memory abilities. The successful formation of the metal-ligand complex was proven by Fourier transform infrared (FT-IR) spectroscopy and by 1H NMR spectroscopy. Furthermore, the shape-recovery behavior was studied in detailed fashion and even triple-shape memory behavior could be revealed.
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    Magnetic-responsive bendable nozzles for open surface droplet manipulation
    (Basel : MDPI, 2019) Prieto-López, L.O.; Xu, J.; Cui, J.
    The handling of droplets in a controlled manner is essential to numerous technological and scientific applications. In this work, we present a new open-surface platform for droplet manipulation based on an array of bendable nozzles that are dynamically controlled by a magnetic field. The actuation of these nozzles is possible thanks to the magnetically responsive elastomeric composite which forms the tips of the nozzles; this is fabricated with Fe3O4 microparticles embedded in a polydimethylsiloxane matrix. The transport, mixing, and splitting of droplets can be controlled by bringing together and separating the tips of these nozzles under the action of a magnet. Additionally, the characteristic configuration for droplet mixing in this platform harnesses the kinetic energy from the feeding streams; this provided a remarkable reduction of 80% in the mixing time between drops of liquids about eight times more viscous than water, i.e., 6.5 mPa/s, when compared against the mixing between sessile drops of the same fluids. © 2019 by the authors.