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- ItemHighly Conductive, Stretchable, and Cell-Adhesive Hydrogel by Nanoclay Doping(Weinheim : Wiley-VCH, 2019) Tondera, Christoph; Akbar, Teuku Fawzul; Thomas, Alvin Kuriakose; Lin, Weilin; Werner, Carsten; Busskamp, Volker; Zhang, Yixin; Minev, Ivan R.Electrically conductive materials that mimic physical and biological properties of tissues are urgently required for seamless brain-machine interfaces. Here, a multinetwork hydrogel combining electrical conductivity of 26 S m-1 , stretchability of 800%, and tissue-like elastic modulus of 15 kPa with mimicry of the extracellular matrix is reported. Engineering this unique set of properties is enabled by a novel in-scaffold polymerization approach. Colloidal hydrogels of the nanoclay Laponite are employed as supports for the assembly of secondary polymer networks. Laponite dramatically increases the conductivity of in-scaffold polymerized poly(ethylene-3,4-diethoxy thiophene) in the absence of other dopants, while preserving excellent stretchability. The scaffold is coated with a layer containing adhesive peptide and polysaccharide dextran sulfate supporting the attachment, proliferation, and neuronal differentiation of human induced pluripotent stem cells directly on the surface of conductive hydrogels. Due to its compatibility with simple extrusion printing, this material promises to enable tissue-mimetic neurostimulating electrodes.
- ItemTopographical anisotropy and wetting of ground stainless steel surfaces(Basel : MDPI AG, 2012) Calvimontes, A.; Mauermann, M.; Bellmann, C.Microscopic and physico-chemical methods were used for a comprehensive surface characterization of different mechanically modified stainless steel surfaces. The surfaces were analyzed using high-resolution confocal microscopy, resulting in detailed information about the topographic properties. In addition, static water contact angle measurements were carried out to characterize the surface heterogeneity of the samples. The effect of morphological anisotropy on water contact angle anisotropy was investigated. The correlation between topography and wetting was studied by means of a model of wetting proposed in the present work, that allows quantifying the air volume of the interface water drop-stainless steel surface.
- ItemVerbundprojekt: Entwicklung polymerer Nanokomposite mit gleichzeitig verbesserten mechanischen und elektrischen Eigenschaften (COMPOMEL), Teilprojekt: Stofflich-verfahrenstechnische Zusammenhänge beim Schmelzemischen : Schlussbericht(Hannover : Technische Informationsbibliothek (TIB), 2011) Pötschke, Petra[no abstract available]
- ItemLiquid sensing: Smart polymer/CNT composites(Amsterdam [u.a.] : Elsevier, 2011) Villmow, T.; Pegel, S.; John, A.; Rentenberger, R.; Pötschke, P.Today polymer/carbon nanotube (CNT) composites can be found in sports equipment, cars, and electronic devices. The growth of old and new markets in this area has been stimulated by our increased understanding of relevant production and processing methods, as well as the considerable price reduction of industrial CNT grades. In particular, CNT based electrically conductive polymer composites (CPCs) offer a range of opportunities because of their unique property profile; they demonstrate low specific gravity in combination with relatively good mechanical properties and processability. The electrical conductivity of polymer/CNT composites results from a continuous filler network that can be affected by various external stimuli, such as temperature shifts, mechanical deformations, and the presence of gases and vapors or solvents. Accordingly, CNT based CPCs represent promising candidates for the design of smart components capable of integrated monitoring. In this article we focus on their use as leakage detectors for organic solvents.
- ItemEinsatz von auf Graphen basierenden Füllstoffen zur Herstellung von neuartigen Elastomerkompositen : Abschlussbericht zum Projekt: ELAGRA - Elastomer Komposite auf Basis von Graphenen ; Laufzeit des Vorhabens: 1.8.2010 - 30.4.2013(Hannover : Technische Informationsbibliothek (TIB), 2013) IPF[no abstract available]
- ItemOrganophile strukturierte Metalloberflächen für reproduzierbare und langlebige Klebungen : Schlussbericht zu dem über die AIF im Rahmen des Programms zur Förderung der industriellen Gemeinschaftsforschung und -entwicklung (IGF) ... geförderten Vorhaben IGF 368 ZBR ; (Bewilligungszeitraum: 01.05.2010 - 31.03.2013)(Dresden : Leibniz-Institut für Polymerforschung, 2013) Simon, Frank; Jansen, Irene[no abstract available]
- ItemCharge inversion effects in electrophoresis of polyelectrolytes in the presence of multivalent counterions and transversal electric fields(Basel : MDPI AG, 2014) Nedelcu, S.; Sommer, J.-U.By molecular dynamics simulations we investigate the transport of charged polymers in confinement, under externally applied electric fields, in straight cylinders of uniform diameter and in the presence of monovalent or multivalent counterions. The applied electric field has two components; a longitudinal component along the axis of the cylinder and a transversal component perpendicular to the cylinder axis. The direction of electrophoretic velocity depends on the polyelectrolyte length, valency of the counterions present in solution and transversal electric field value. A statistical model is put forward in order to explain these observations.
- ItemOn the anomalous optical conductivity dispersion of electrically conducting polymers: Ultra-wide spectral range ellipsometry combined with a Drude-Lorentz model(London [u.a.] : RSC, 2019) Chen, Shangzhi; Kühne, Philipp; Stanishev, Vallery; Knight, Sean; Brooke, Robert; Petsagkourakis, Ioannis; Crispin, Xavier; Schubert, Mathias; Darakchieva, Vanya; Jonsson, Magnus P.Electrically conducting polymers (ECPs) are becoming increasingly important in areas such as optoelectronics, biomedical devices, and energy systems. Still, their detailed charge transport properties produce an anomalous optical conductivity dispersion that is not yet fully understood in terms of physical model equations for the broad range optical response. Several modifications to the classical Drude model have been proposed to account for a strong non-Drude behavior from terahertz (THz) to infrared (IR) ranges, typically by implementing negative amplitude oscillator functions to the model dielectric function that effectively reduce the conductivity in those ranges. Here we present an alternative description that modifies the Drude model via addition of positive-amplitude Lorentz oscillator functions. We evaluate this so-called Drude-Lorentz (DL) model based on the first ultra-wide spectral range ellipsometry study of ECPs, spanning over four orders of magnitude: from 0.41 meV in the THz range to 5.90 eV in the ultraviolet range, using thin films of poly(3,4-ethylenedioxythiophene):tosylate (PEDOT:Tos) as a model system. The model could accurately fit the experimental data in the whole ultrawide spectral range and provide the complex anisotropic optical conductivity of the material. Examining the resonance frequencies and widths of the Lorentz oscillators reveals that both spectrally narrow vibrational resonances and broader resonances due to localization processes contribute significantly to the deviation from the Drude optical conductivity dispersion. As verified by independent electrical measurements, the DL model accurately determines the electrical properties of the thin film, including DC conductivity, charge density, and (anisotropic) mobility. The ellipsometric method combined with the DL model may thereby become an effective and reliable tool in determining both optical and electrical properties of ECPs, indicating its future potential as a contact-free alternative to traditional electrical characterization. © The Royal Society of Chemistry 2019.
- ItemAbschlussbericht zum BMBF Verbundprojekt: Kompetenznetzwerk für Nanosystemintegration: Anwendung von Nanotechnologien für energieeffiziente Sensorsysteme zu dem Teilvorhaben: LPC-Materialintegrierte Sensorik basierend auf Nanoeffekten - Entwicklung multifunktionaler Polymernanokompositestrukturen ; Laufzeit: 01.11.2009 bis 31.10.2012(Hannover : Technische Informationsbibliothek (TIB), 2012) Voit, Brigitte; Staudinger, Ulrike; Müller, Michael Thomas; Demir, Emrah; Pötschke, Petra[no abstract available]
- ItemFluidischer Partikel-Transport an Grenzflächen durch aktorisch bewegte Mikrohaare mit schaltbarer Nanostrukturierung - PaTra, Teilvorhaben: Funktionale Nanostrukturen : Abschlussbericht ; Berichtszeitraum: 01.04.2011 - 31.03.2014(Hannover : Technische Informationsbibliothek (TIB), 2014) Uhlmann, Petra; Kunder, Mandy; Rollberg, Anja; Bittrich, Eva; Rauch, Sebastian; König, Ulla[no abstract available]