Highlight Publications 2017

Stable Hydrophobic Metal-Oxide Photocatalysts via Grafting Polydimethylsiloxane Brush
Sanghyuk Wooh, Noemí Encinas, Doris Vollmer, and Hans-Jürgen Butt
Stable Hydrophobic Metal-Oxide Photocatalysts via Grafting Polydimethylsiloxane Brush
We designed a new method for grafting polydimethylsiloxane (PDMS) on surfaces of metal-oxide photocatalysts via simple illumination. By this PDMS grating reaction, stable photocatalytically active liquid-repellent surfaces were realized. The PDMS grafted metal-oxide photocatalysts exhibited improved self-cleaning and anti-biofouling properties by the combination effect of photocatalytic activity and liquid-repellency.
© WILEY-VCH (2017)
The photocatalytically active liquid-repellent surfaces were introduced by developing PDMS grafting reaction on metal-oxide photocatalysts.
Structure–Property Relations of Methylamine Vapor Treated Hybrid Perovskite CH3NH3PbI3 Films and Solar Cells
Bert Conings, Simon A. Bretschneider, Aslihan Babayigit, Nicolas Gauquelin, Ilaria Cardinaletti, Jean Manca, Jo Verbeeck, Henry J Snaith, Hans-Gerd Boyen
Structure–Property Relations of Methylamine Vapor Treated Hybrid Perovskite CH3NH3PbI3 Films and Solar Cells
The power conversion efficiency of halide perovskite solar cells is heavily dependent on the perovskite layer being sufficiently smooth and pinhole-free. It has been shown that these features can be obtained even when starting out from rough and discontinuous perovskite film by briefly exposing the film to methylamine (MA) vapor. The exact underlying physical mechanisms of this phenomenon are, however, still unclear. By investigating smooth, MA treated films based on very rough and discontinuous reference films of methylammonium triiode (MAPbI3) and considering their morphology, crystalline features, local conductive properties, and charge carrier lifetime, we unraveled the relation between their characteristic physical qualities and their performance in corresponding solar cells. We discovered that the extensive improvement in photovoltaic performance upon MA treatment is a consequence of the induced morphological enhancement of the perovskite layer together with improved electron injection into TiO2, which in fact compensates for an otherwise compromised bulk electronic quality simultaneously caused by the MA treatment.
© American Chemical Society (2017)
Methylamine treatment of sensitized perovskite solar cells facilitates the infiltration of the perovskite into the TiO2 and evens out the perovskite capping layer to reduce shunting, resulting in a dramatic improvement of the efficiency.
Shape Controlled Hierarchical Porous Hydrophobic/Oleophilic Metal-Organic Nanofibrous Gel Composites for Oil Adsorption
Kolleboyina Jayaramulu, Florian Geyer, Martin Petr, Radek Zboril, Doris Vollmer, Roland A. Fischer
Shape Controlled Hierarchical Porous Hydrophobic/Oleophilic Metal-Organic Nanofibrous Gel Composites for Oil Adsorption
We designed a simple route to synthesize hydrophobic and superoleophilic, fibrous hierarchically porous hybrid materials composed of metal organic gels (MOGs) with fluorinated graphene oxide (FGO). The integration of FGO layer stacks to light MOGs has proven a great asset in combining functional features and enhancement of materials performance.
© Advanced Materials (2017)
Schematic illustration of the formation of FGO@MOG (top). Coordination perturbation, selective functionalization of MOF-nanoparticles with FGO yields a hybrid composite gel. Water drop (6 µL) on pressed FGO@MOG tablet (bottom left). Oil is adsorbed by the composite material (bottom right).
On-Surface Synthesis and Characterization of 9-Atom Wide Armchair Graphene Nanoribbons
Leopold Talirz, Hajo Söde, Tim Dumslaff, Shiyong Wang, Juan Ramon Sanchez-Valencia, Jia Liu, Prashant Shinde, Carlo A. Pignedoli, Liangbo Liang, Vincent Meunier, Nicholas C. Plumb, Ming Shi, Xinliang Feng, Akimitsu Narita, Klaus Müllen, Roman Fasel, Pascal Ruffieux
On-Surface Synthesis and Characterization of 9-Atom Wide Armchair Graphene Nanoribbons
We present the synthesis of 9-atom-wide armchair-edge GNRs (9-AGNRs) via surface-assisted aryl-aryl coupling and cyclodehydrogenation of a small halogen-substituted precursor molecule on Au(111). In this approach, the molecular precursor precisely defines the width and edge structure of the resulting GNRs down to the single atom, thus providing ultimate control over the band gap by design. We have designed and synthesize suitable monomer with an o-terphenyl-based structure, which selectively provided atomically precise 9-AGNRs as revealed by scanning probe microscopy and Raman spectroscopy. In line with theoretical predictions of their electronic properties, a low band gap of 1.4 eV and small effective masses of 0.1 me for electrons and holes are found for the metal-adsorbed 9-AGNRs, making them an interesting material for room-temperature electronic and optoelectronic switching devices
© American Chemical Society (2017)
High-resolution nc-AFM frequency shift image of 9-AGNR using a CO-functionalized tip with oscillation amplitude of 70 pm (scale bar: 1 nm).
Small Activity Differences Drive Phase Separation in Active-Passive Polymer Mixtures
Jan Smrek and Kurt Kremer
Small Activity Differences Drive Phase Separation in Active-Passive Polymer Mixtures
Recent theoretical studies found that mixtures of active and passive colloidal particles phase separate but only at very high activity ratio. The high value poses serious obstacles for experimental exploration of this phenomenon. Here we show using simulations that when the active and passive particles are polymers, the critical activity ratio decreases with the polymer length. This not only facilitates the experiments but also has implications on the DNA organization in living cell nuclei. Entropy production can be used as an accurate indicator of this nonequilibrium phase transition.
© Jan Smrek and Kurt Kremer (2017)
An initial mixture (left) of active (black) and inactive (yellow) chains spontaneously phase separates into steady state composed of active and passive phases (right).
50th Anniversary Perspective: The Importance of NMR Spectroscopy to Macromolecular Science
Hans Wolfgang Spiess
50th Anniversary Perspective: The Importance of NMR Spectroscopy to Macromolecular Science
This invited Perspective Article for the 50th Anniversary Issue of Macromolecules describes the remarkable development of NMR spectroscopy during the past 50 years with emphasis on applications in macromolecular science. The article cites colleagues from academia and industry, who refer to NMR as a ‘premier technique for polymer studies’. The Max Planck Institute for Polymer Research has significantly contributed to this development. Today NMR spectroscopy is as vibrant as ever and recent advances allow the study of more and more complex molecular as well as materials problems.
© ACS (2017)
During the last 50 years NMR spectroscopy has undergone an unprecedented development as described in the Perspective Article entitled “The Importance of NMR Spectroscopy to Macromolecular Science”.
 
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