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Author: Al-Hussein, Mahmoud × DDC: 540 ×

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Now showing 1 - 3 of 3
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    Reversible thermosensitive biodegradable polymeric actuators based on confined crystallization
    (Washington, DC : ACS Publ., 2015) Stroganov, Vladislav; Al-Hussein, Mahmoud; Sommer, Jens-Uwe; Janke, Andreas; Zakharchenko, Svetlana; Ionov, Leonid
    We discovered a new and unexpected effect of reversible actuation of ultrathin semicrystalline polymer films. The principle was demonstrated on the example of thin polycaprolactone-gelatin bilayer films. These films are unfolded at room temperature, fold at temperature above polycaprolactone melting point, and unfold again at room temperature. The actuation is based on reversible switching of the structure of the hydrophobic polymer (polycaprolactone) upon melting and crystallization. We hypothesize that the origin of this unexpected behavior is the orientation of polycaprolactone chains parallel to the surface of the film, which is retained even after melting and crystallization of the polymer or the “crystallization memory effect”. In this way, the crystallization generates a directed force, which causes bending of the film. We used this effect for the design of new generation of fully biodegradable thermoresponsive polymeric actuators, which are highly desirable for bionano-technological applications such as reversible encapsulation of cells and design of swimmers.
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    Copolymerization of zinc-activated isoindigo- and naphthalene-diimide based monomers: an efficient route to low bandgap π-conjugated random copolymers with tunable properties
    (Cambridge : RSC Publ., 2016) Karpov, Yevhen; Maiti, Jatindranath; Tkachov, Roman; Beryozkina, Tetyana; Bakulev, Vasiliy; Liu, Wei; Komber, Hartmut; Lappan, Uwe; Al-Hussein, Mahmoud; Stamm, Manfred; Voit, Brigitte; Kiriy, Anton
    The present work aims at the extension of the scope of a recently discovered polycondensation of AB-type anion-radical monomers. To this end, we investigate the polymerization of isoindigo-based monomer and its copolymerization with the naphthalenediimide-based monomer. Although polycondensations of parent naphthalenediimide- and perylenediimide-based monomers involve chain-growth mechanism, we found that the corresponding isoindigo-based monomer polymerizes in a step-growth manner under the same reaction conditions. In contrast to Stille, Suzuki and direct arylation polycondensations which require prolonged stirring at high temperatures, the polymerization approach we employed in this study proceeds fast at room temperature. It was found that near statistical copolymerization of isoindigo-based anion-radical monomers with corresponding naphtalenediimide-based monomers proceeds smoothly resulting in a library of copolymers with varying composition and properties depending on the ratio of the monomers.
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    Ultrasoft and High-Mobility Block Copolymers for Skin-Compatible Electronics
    (Weinheim : Wiley-VCH, 2020) Ditte, Kristina; Perez, Jonathan; Chae, Soosang; Hambsch, Mike; Al-Hussein, Mahmoud; Komber, Hartmut; Formanek, Peter; Mannsfeld, Stefan C.B.; Fery, Andreas; Kiriy, Anton; Lissel, Franziska
    Polymer semiconductors (PSCs) are an essential component of organic field-effect transistors (OFETs), but their potential for stretchable electronics is limited by their brittleness and failure susceptibility upon strain. Herein, a covalent connection of two state-of-the-art polymers—semiconducting poly-diketo-pyrrolopyrrole-thienothiophene (PDPP-TT) and elastomeric poly(dimethylsiloxane) (PDMS)—in a single triblock copolymer (TBC) chain is reported, which enables high charge carrier mobility and low modulus in one system. Three TBCs containing up to 65 wt% PDMS were obtained, and the TBC with 65 wt% PDMS content exhibits mobilities up to 0.1 cm2 V−1 s−1, in the range of the fully conjugated reference polymer PDPP-TT (0.7 cm2 V−1 s−1). The TBC is ultrasoft with a low elastic modulus (5 MPa) in the range of mammalian tissue. The TBC exhibits an excellent stretchability and extraordinary durability, fully maintaining the initial electric conductivity in a doped state after 1500 cycles to 50% strain. © 2020 The Authors. Advanced Materials published by Wiley-VCH GmbH