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DDC: 540 × Type: Text × search.filters.applied.f.series: Polymers 10 (2018), Nr. 1 ×

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Now showing 1 - 4 of 4
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    Novel Antibacterial Polyglycidols: Relationship between Structure and Properties
    (Basel : MDPI, 2018) Marquardt, Fabian; Stöcker, Cornelia; Gartzen, Rita; Heine, Elisabeth; Keul, Helmut; Möller, Martin
    Antimicrobial polymers are an attractive alternative to low molecular weight biocides, because they are non-volatile, chemically stable, and can be used as non-releasing additives. Polymers with pendant quaternary ammonium groups and hydrophobic chains exhibit antimicrobial properties due to the electrostatic interaction between polymer and cell wall, and the membrane disruptive capabilities of the hydrophobic moiety. Herein, the synthesis of cationic–hydrophobic polyglycidols with varying structures by post-polymerization modification is presented. The antimicrobial properties of the prepared polyglycidols against E. coli and S. aureus are examined. Polyglycidol with statistically distributed cationic and hydrophobic groups (cationic–hydrophobic balance of 1:1) is compared to (i) polyglycidol with a hydrophilic modification at the cationic functionality; (ii) polyglycidol with both—cationic and hydrophobic groups—at every repeating unit; and (iii) polyglycidol with a cationic–hydrophobic balance of 1:2. A relationship between structure and properties is presented.
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    Temperature Scanning Stress Relaxation of an Autonomous Self-Healing Elastomer Containing Non-Covalent Reversible Network Junctions
    (Basel : MDPI, 2018-01-19) Das, Amit; Sallat, Aladdin; Böhme, Frank; Sarlin, Essi; Vuorinen, Jyrki; Vennemann, Norbert; Heinrich, Gert; Stöckelhuber, Klaus Werner
    In this work, we report about the mechanical relaxation characteristics of an intrinsically self-healable imidazole modified commercial rubber. This kind of self-healing rubber was prepared by melt mixing of 1-butyl imidazole with bromo-butyl rubber (bromine modified isoprene-isobutylene copolymer, BIIR). By this melt mixing process, the reactive allylic bromine of bromo-butyl rubber was converted into imidazole bromide salt. The resulting development of an ionic character to the polymer backbone leads to an ionic association of the groups which ultimately results to the formation of a network structure of the rubber chains. The modified BIIR thus behaves like a robust crosslinked rubber and shows unusual self-healing properties. The non-covalent reversible network has been studied in detail with respect to stress relaxation experiments, scanning electron microscopic and X-ray scattering.
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    Improving Kinetics of “Click-Crosslinking” for Self-Healing Nanocomposites by Graphene-Supported Cu-Nanoparticles
    (Basel : MDPI, 2017) Kargarfard, Neda; Diedrich, Norman; Rupp, Harald; Döhler, Diana; Binder, Wolfgang H.
    Investigation of the curing kinetics of crosslinking reactions and the development of optimized catalyst systems is of importance for the preparation of self-healing nanocomposites, able to significantly extend their service lifetimes. Here we study different modified low molecular weight multivalent azides for a capsule-based self-healing approach, where self-healing is mediated by graphene-supported copper-nanoparticles, able to trigger “click”-based crosslinking of trivalent azides and alkynes. When monitoring the reaction kinetics of the curing reaction via reactive dynamic scanning calorimetry (DSC), it was found that the “click-crosslinking” reactivity decreased with increasing chain length of the according azide. Additionally, we could show a remarkable “click” reactivity already at 0 °C, highlighting the potential of click-based self-healing approaches. Furthermore, we varied the reaction temperature during the preparation of our tailor-made graphene-based copper(I) catalyst to further optimize its catalytic activity. With the most active catalyst prepared at 700 °C and the optimized set-up of reactants on hand, we prepared capsule-based self-healing epoxy nanocomposites.
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    Solubility, Emulsification and Surface Properties of Maleic Anhydride, Perfluorooctyl and Alkyl Meth-Acrylate Terpolymers
    (Basel : MDPI, 2018) Szkudlarek, Marian; Beginn, Uwe; Keul, Helmut; Möller, Martin
    The solubility of terpolymers containing alkyl, and perfluoroalkyl side chains as well as succinic acid moieties in the main chain, P[RFMA0.2-co-RHMA0.65-co-MAH0.15] (RH = C4H9- or C12H25-, RF- = C10H4F19-) with ca. 20 mol % fluorinated side chains and 10–22 mol % of succinic anhydride rings was tested in a number of solvents varying from water to non polar mineral oils. The polymers are well soluble in fluorinated solvents like Freon-113® and 1,3-bis(trifluoromethyl) benzene, in semi-polar solvents like chloroform, THF or lower esters and also in hydrocarbons with polymers containing dodecyl methacrylate. In self-emulsification experiments, a stable water emulsion of P[F8H2MA0.2-co-BMA0.65-co-MAH0.15] was obtained. The dispersability and emulsification of these polymers in mixtures of organic solvents and water yielded stable emulsions in the presence of additional surfactant. Thin films coated from organic solutions as well as from emulsions on glass resulted in water and oil-repelling surfaces with contact angles up to 140° against water and 71° against hexadecane. An enhancing effect of annealing was not observed.