TY - JOUR A1 - Inal, Sahika A1 - Chiappisi, Leonardo A1 - Kölsch, Jonas D. A1 - Kraft, Mario A1 - Appavou, Marie-Sousai A1 - Scherf, Ullrich A1 - Wagner, Manfred A1 - Hansen, Michael Ryan A1 - Gradzielski, Michael A1 - Laschewsky, André A1 - Neher, Dieter T1 - Temperature-regulated fluorescence and association of an Oligo(ethyleneglycol)methacrylate-based copolymer with a conjugated Polyelectrolyte-the effect of solution ionic strength JF - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry N2 - Aqueous mixtures of a dye-labeled non-ionic thermoresponsive copolymer and a conjugated cationic polyelectrolyte are shown to exhibit characteristic changes in fluorescence properties in response to temperature and to the presence of salts, enabling a double-stimuli responsiveness. In such mixtures at room temperature, i.e., well below the lower critical solution temperature (LCST), the emission of the dye is strongly quenched due to energy transfer to the polycation, pointing to supramolecular interactions between the two macromolecules. Increasing the concentration of salts weakens the interpolymer interactions, the extent of which is simultaneously monitored from the change in the relative emission intensity of the components. When the mixture is heated above its LCST, the transfer efficiency is significantly reduced, signaling a structural reorganization process, however, surprisingly only if the mixture contains salt ions. To elucidate the reasons behind such thermo- and ion-sensitive fluorescence characteristics, we investigate the effect of salts of alkali chlorides, in particular of NaCl, on the association behavior of these macromolecules before and after the polymer phase transition by a combination of UV-vis, fluorescence, and H-1 NMR spectroscopy with light scattering and small-angle neutron scattering measurements. Y1 - 2013 U6 - https://doi.org/10.1021/jp408864s SN - 1520-6106 VL - 117 IS - 46 SP - 14576 EP - 14587 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Koehler, Friedrich A1 - Koehler, Kerstin A1 - Deckwart, Oliver A1 - Prescher, Sandra A1 - Wegscheider, Karl A1 - Winkler, Sebastian A1 - Vettorazzi, Eik A1 - Polze, Andreas A1 - Stangl, Karl A1 - Hartmann, Oliver A1 - Marx, Almuth A1 - Neuhaus, Petra A1 - Scherf, Michael A1 - Kirwan, Bridget-Anne A1 - Anker, Stefan D. T1 - Telemedical Interventional Management in Heart Failure II (TIM-HF2), a randomised, controlled trial investigating the impact of telemedicine on unplanned cardiovascular hospitalisations and mortality in heart failure patients BT - study design and description of the intervention JF - European Journal of Heart Failure N2 - Background Heart failure (HF) is a complex, chronic condition that is associated with debilitating symptoms, all of which necessitate close follow-up by health care providers. Lack of disease monitoring may result in increased mortality and more frequent hospital readmissions for decompensated HF. Remote patient management (RPM) in this patient population may help to detect early signs and symptoms of cardiac decompensation, thus enabling a prompt initiation of the appropriate treatment and care before a manifestation of HF decompensation. Objective The objective of the present article is to describe the design of a new trial investigating the impact of RPM on unplanned cardiovascular hospitalisations and mortality in HF patients. Methods The TIM-HF2 trial is designed as a prospective, randomised, controlled, parallel group, open (with randomisation concealment), multicentre trial with pragmatic elements introduced for data collection. Eligible patients with HF are randomised (1:1) to either RPM + usual care or to usual care only and are followed for 12 months. The primary outcome is the percentage of days lost due to unplanned cardiovascular hospitalisations or all-cause death. The main secondary outcomes are all-cause and cardiovascular mortality. Conclusion The TIM-HF2 trial will provide important prospective data on the potential beneficial effect of telemedical monitoring and RPM on unplanned cardiovascular hospitalisations and mortality in HF patients. KW - Chronic heart failure KW - Telemonitoring KW - Remote patient management KW - Hospitalisation Y1 - 2018 U6 - https://doi.org/10.1002/ejhf.1300 SN - 1388-9842 SN - 1879-0844 VL - 20 IS - 10 SP - 1485 EP - 1493 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Inal, Sahika A1 - Koelsch, Jonas D. A1 - Chiappisi, Leonardo A1 - Kraft, Mario A1 - Gutacker, Andrea A1 - Janietz, Dietmar A1 - Scherf, Ullrich A1 - Gradzielski, Michael A1 - Laschewsky, André A1 - Neher, Dieter T1 - Temperature-Regulated Fluorescence Characteristics of Supramolecular Assemblies Formed By a Smart Polymer and a Conjugated Polyelectrolyte JF - MACROMOLECULAR CHEMISTRY AND PHYSICS N2 - Aqueous mixtures of a coumarin-labeled non-ionic thermoresponsive copolymer and a cationic polythiophene exhibit marked changes in their fluorescence properties upon heating. At room temperature, emission from the label is significantly quenched due to energy transfer to the conjugated polyelectrolyte. Heating the mixture reduces the energy-transfer efficiency markedly, resulting in a clearly visible change of the emission color. Although the two macromolecules associate strongly at room temperature, the number of interacting sites is largely reduced upon the phase transition. Crucially, the intermolecular association does not suppress the responsiveness of the smart polymer, meaning that this concept should be applicable to chemo- or bioresponsive polymers with optical read-out, for example, as a sensor device. KW - aqueous solutions KW - conjugated polyelectrolytes KW - fluorescence (or Forster) KW - resonance energy transfer KW - phase transitions KW - thermoresponsive polymers Y1 - 2013 U6 - https://doi.org/10.1002/macp.201200493 SN - 1022-1352 VL - 214 IS - 4 SP - 435 EP - 445 PB - WILEY-V C H VERLAG GMBH CY - WEINHEIM ER - TY - JOUR A1 - Joshi, Siddharth A1 - Pingel, Patrick A1 - Grigorian, Souren A1 - Panzner, Tobias A1 - Pietsch, Ullrich A1 - Neher, Dieter A1 - Forster, Michael A1 - Scherf, Ullrich T1 - Bimodal temperature behavior of structure and mobility in high molecular weight p3ht thin films N2 - We report a temperature dependent crystalline structure of spin-coated thin films of high molecular weight regioregular poly(3-hexylthiophene) (P3HT) (M-n similar to 30000 g/mol) and its correlation with charge carrier mobility. These investigations show a reversible change of the crystalline structure, where the interlayer lattice spacing (100)along the alkyl side chains continuously increases up to a temperature of about 220 degrees C; in contrast, the in-plane pi-pi distance reduces with increasing temperature. These changes in structure are reversible and can be repeated several times. The temperature-induced structural properties differ for thick and thin films, pointing to a surface/interface role in stabilization of the layer morphology. In contrast to the structural changes, the carrier mobility is rather constant in the temperature range from room temperature up to 100-120 degrees C, followed by a continuous decrease. For thick layers this drop is significant and the transistor performance almost vanishes at high temperature, however, it completely recovers upon cooling back to roorn temperature. The drop of the charge carrier mobility at higher temperatures is in contrast with expectations front the structural studies, considering the increase of crystalline fraction of the polycrystalline layer. our electrical measurements Underscore that the reduction of the macroscopic mobility is mostly caused by it pronounced decrease of the intergrain transport. The thermally induced crystallization along(100) direction and the creation of numerous small crystallites at the film-substrate interface reduce the number of long polymer chain, bridging crystalline domains, which ultimately limits the macroscopic charge transport. Y1 - 2009 UR - http://pubs.acs.org/journal/mamobx U6 - https://doi.org/10.1021/Ma900021w SN - 0024-9297 ER - TY - JOUR A1 - Scharsich, Christina A1 - Lohwasser, Ruth H. A1 - Sommer, Michael A1 - Asawapirom, Udom A1 - Scherf, Ullrich A1 - Thelakkat, Mukundan A1 - Neher, Dieter A1 - Koehler, Anna T1 - Control of aggregate formation in poly(3-hexylthiophene) by solvent, molecular weight, and synthetic method JF - Journal of polymer science : B, Polymer physics N2 - Aggregate formation in poly(3-hexylthiophene) depends on molecular weight, solvent, and synthetic method. The interplay of these parameters thus largely controls device performance. In order to obtain a quantitative understanding on how these factors control the resulting electronic properties of P3HT, we measured absorption in solution and in thin films as well as the resulting field effect mobility in transistors. By a detailed analysis of the absorption spectra, we deduce the fraction of aggregates formed, the excitonic coupling within the aggregates, and the conjugation length within the aggregates, all as a function of solvent quality for molecular weights from 5 to 19 kDa. From this, we infer in which structure the aggregated chains pack. Although the 5 kDa samples form straight chains, the 11 and 19 kDa chains are kinked or folded, with conjugation lengths that increase as the solvent quality reduces. There is a maximum fraction of aggregated chains (about 55 +/- 5%) that can be obtained, even for poor solvent quality. We show that inducing aggregation in solution leads to control of aggregate properties in thin films. As expected, the field-effect mobility correlates with the propensity to aggregation. Correspondingly, we find that a well-defined synthetic approach, tailored to give a narrow molecular weight distribution, is needed to obtain high field effect mobilities of up to 0.01 cm2/Vs for low molecular weight samples (=11 kDa), while the influence of synthetic method is negligible for samples of higher molecular weight, if low molecular weight fractions are removed by extraction. KW - conformational analysis KW - conjugated polymers KW - crystallization KW - films KW - interaction parameter KW - molecular weight distribution KW - molar mass distribution KW - nucleation KW - photophysics KW - structure KW - UV-vis spectroscopy Y1 - 2012 U6 - https://doi.org/10.1002/polb.23022 SN - 0887-6266 VL - 50 IS - 6 SP - 442 EP - 453 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Kietzke, Thomas A1 - Neher, Dieter A1 - Kumke, Michael Uwe A1 - Montenegro, Rivelino V. D. A1 - Landfester, Katharina A1 - Scherf, Ullrich T1 - A nanoparticle approach to control the phase separation in polyfluorene photovoltaic devices N2 - Polymer solar cell devices with nanostructured blend layers have been fabricated using single- and dual- component polymer nanospheres. Starting from an electron-donating and an electron-accepting polyfluorene derivative, PFB and F8BT, dissolved in suitable organic solvents, dispersions of solid particles with mean diameters of ca. 50 nm, containing either the pure polymer components or a mixture of PFB and F8BT in each particle, were prepared with the miniemulsion process. Photovoltaic devices based on these particles have been studied with respect to the correlation between external quantum efficiency and layer composition. It is shown that the properties of devices containing a blend of single-component PFB and F8BT particles differ significantly from those of solar cells based on blend particles, even for the same layer composition. Various factors determining the quantum efficiency in both kinds of devices are identified and discussed, taking into account the spectroscopic properties of the particles. An external quantum efficiency of ca. 4% is measured for a device made from polymer blend nanoparticles containing PFB:F8BT at a weight ratio of 1:2 in each individual nanosphere. This is among the highest values reported so far for photovoltaic cells using this material combination Y1 - 2004 ER - TY - JOUR A1 - Yang, Xiao Hui A1 - Jaiser, Frank A1 - Neher, Dieter A1 - Lawson, PaDreyia V. A1 - Brédas, Jean-Luc A1 - Zojer, Egbert A1 - Güntner, Roland A1 - Scanduicci de Freitas, Patricia A1 - Forster, Michael A1 - Scherf, Ullrich T1 - Suppression of the keto-emission in polyfluorene light-emitting diodes : Experiments and models N2 - The spectral characteristics of polyfluorene (PF)-based light-emitting diodes (LEDs) containing a defined low concentration of either keto-defects or of the polymer poly(9.9-octylfuorene-co-benzothiadiazole) (F8BT) are preseneted. Both types of blend layers were tested in different device configurations with respect to the relative and absolute intensities of green blue emission components. It is shown that blending hole-transporting molecules into the emission layer at low concentration or incorporation of a suitable hole-transport layer reduces the green emission contribution in the electroluminescence (EL) spectrum of the PF:F8BT blend, which is similar to what is observed for the keto- containing PF layer. We conclude that the keto-defects in PF homopolymer layers mainly constitute weakly emissive electron traps, in agreement with the results of quantum-mechanical calculations Y1 - 2004 SN - 1616-301X ER -