Highlight Publications 2017

Reversible Self-Assembly of Degradable Polymersomes with Upper Critical Solution Temperature in Water
Thomas Wolf, Timo Rheinberger, Johanna Simon, Frederik R. Wurm
Reversible Self-Assembly of Degradable Polymersomes with Upper Critical Solution Temperature in Water
Temperature-induced self-assembly of block copolymers allows the formation of smart nanodimensional structures. Mostly, non-degradable LCST segments are used to prepare such dynamic aggregates. However, degradable UCST block copolymers that would allow the swelling or disassembly at elevated temperatures with eventual backbone hydrolysis have not been reported to date. We present the first well-defined degradable poly(phosphonate)s with adjustable UCST in water between 43 °C and 71 °C. Block copolymers with PEG self-assemble into well-defined polymersomes. Depending on the responsive block, these structures either swell or disassemble completely upon an increased temperature.
© ACS (2017)
Upper critical solution temperature in degradable poly(phosphoester)s was installed to prepare block copolymer vesicles that self-assemble at room temperature and reversibly disassemble at elevated temperatures.
A Conjugated Microporous Polymer for Palladium-Free, Visible Light-Promoted Photocatalytic Stille-Type Coupling Reactions
Saman Ghasimi, Simon A. Bretschneider, Wei Huang, Katharina Landfester, and Kai A. I. Zhang
A Conjugated Microporous Polymer for Palladium-Free, Visible Light-Promoted Photocatalytic Stille-Type Coupling Reactions
The Stille coupling reaction is a versatile method to mainly form aromatic C-C bonds. However, up to now, the use of palladium catalysts is necessary. Researchers from the MPI-P reported a palladium-free and photocatalytic Stille-type coupling route between aryl iodides and aryl stannanes. The new coupling reaction pathway is catalyzed by a conjugated microporous polymer under visible light irradiation at room temperature. The novel coupling reaction mechanism occurs between the photogenerated aryl radical under oxidative destannylation of the aryl stannane, and the electron-activated aryl iodide, resulting into the aromatic C-C bond formation reaction.
© Wiley VCH (2017)
Bye-Bye Palladium: A photocatalytic, palladium-free Stille-type coupling reaction is described.
A triaxial supramolecular weave
Urszula Lewandowska, Wojciech Zajaczkowski, Stefano Corra, Junki Tanabe,Ruediger Borrmann, Edmondo M. Benetti, Sebastian Stappert, Kohei Watanabe, Nellie A. K. Ochs, Robin Schaeublin, Chen Li, Eiji Yashima, Wojciech Pisula, Klaus Müllen & Helma Wennemers
A triaxial supramolecular weave
Despite recent advances in the synthesis of increasingly complex topologies at the molecular level, nano- and microscopic weaves have remained difficult to achieve. Only a few diaxial molecular weaves exist these were achieved by templation with metals. Here, we present an extended triaxial supramolecular weave that consists of self-assembled organic threads. Each thread is formed by the self-assembly of a building block comprising a rigid oligoproline segment with two perylene-monoimide chromophores spaced at 18 Å. Upon π stacking of the chromophores, threads form that feature alternating up- and down-facing voids at regular distances. These voids accommodate incoming building blocks and establish crossing points through CH–π interactions on further assembly of the threads into a triaxial woven superstructure. The resulting micrometer-scale supramolecular weave proved to be more robust than non-woven self-assemblies of the same building block. The uniform hexagonal pores of the interwoven network were able to host iridium nanoparticles, which may be of interest for practical applications.
© Helma Wennemers/ETH und Klaus Müllen/MPI-P (2017)
Woven topologies endow macroscopic objects with mechanical stability, but their molecular counterparts have remained difficult to prepare. Now, an extended triaxial supramolecular weave has been formed by the self-assembly of a judiciously shaped organic building block - a rigid oligoproline segment featuring two perylene-monoimide moieties - through π-π stacking and CH-π interactions.
Diffusion and Permeation of Labeled IgG in Grafted Hydrogels
A. Vagias,K. Sergelen,K. Koynov,P. Košovan,J. Dostalek,U. Jonas,W. Knoll,and G. Fytas
Diffusion and Permeation of Labeled IgG in Grafted Hydrogels
The transport of antibodies through hydrogel materials is of fundamental relevance for many biological systems, but equally important in medical and technological applications. With this in mind we used fluorescence correlation spectroscopy (FCS) to study the permeation and diffusion of immunoglobulin G (IgG) in model hydrogel layers based on thermo-responsive poly(N-isopropylacrylamide) (pNiPAAm). Our findings demonstrated the outmost importance of the various interactions between proteins and the polymer network and suggest a model approach to explore the synergy between crowding and thermodynamics with respect to the controlled protein transport in pNiPAAm-based hydrogels.
© ACS (2017)
Schematic illustration of the variability of IgG and PNiPAAm interactions, depending on external stimulus employed: pH, ionic strength (I), temperature (T). IgG trajectory through the FCS focal spot is also depicted.
Solution-Processable High-Quality Graphene for Organic Solar Cells
Antonio Gaetano Ricciardulli, Sheng Yang, Xinliang Feng, Paul W. M. Blom
Solution-Processable High-Quality Graphene for Organic Solar Cells
Researchers from MPIP and TU Dresden report the first example of organic solar cells (OSCs) with a solution-processed transparent electrode based on electrochemical exfoliated graphene (EG). Thanks to the high-quality of EG, the fine control of the morphology and uniformity of the film, the OSCs fabricated in this study exhibit improved features compared to other solution-processable graphene-based organic photovoltaic devices up-to-date. Our work is a step forward toward the application of solution-processable high-quality graphene as transparent electrode in solar cells as well as other organic electronics.
© ACS (2017)
Spray coating of solution-processable graphene and the related solar cell performance
Photoswitchable Micro-Supercapacitor Based on a Diarylethene-Graphene Composite Film
Zhaoyang Liu, Hai I. Wang, Akimitsu Narita, Qiang Chen, Zoltan Mics, Dmitry Turchinovich, Mathias Kläui, Mischa Bonn, and Klaus Müllen
Photoswitchable Micro-Supercapacitor Based on a Diarylethene-Graphene Composite Film
Stimuli-responsive micro-supercapacitors (MSCs) controlled by external stimuli can enable a wide range of applications for future on-chip energy storage. Here, we report on a photoswitchable MSC based on a diarylethene-graphene composite film. The microdevice delivers an outstanding and reversible capacitance modulation of up to 20%, demonstrating a prototype photoswitchable MSC. Terahertz spectroscopy indicates that the photoswitching of the capacitance is enabled by the reversible tuning of interfacial charge injection into diarylethene molecular orbitals, as a consequence of charge transfer at the diarylethene–graphene interface upon light modulation.
© ACS (2017)
Schematic illustration of photoresponsive micro-supercapacitor (MSC) device with Diarylethene (DAE) on the top of graphene electrodes.
 
loading content