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A new straight forward approach to create nanoporous polymer membranes with well defined average pore diameters is presented. The method is based on fast mechanical deformation of highly entangled polymer films at high temperatures and a subsequent quench far below the glass transition temperature Tg. The process is first designed generally by simulation and then verified for the example of polystyrene films. The methodology does not need any chemical processing, supporting substrate, or self assembly process and is solely based on polymer inherent entanglement effects. Pore diameters are of the order of ten polymer reptation tube diameters. The resulting membranes are stable over months at ambient conditions and display remarkable elastic properties. [ABSTRACT FROM AUTHOR]

The effects of the casting speed and solute concentration on the crystallization of 2,7‐dioctyl[1]benzothieno[3,2‐b][1]benzothiophene (C8‐BTBT) during meniscus‐guided coating (MGC) are investigated, and three morphological subregimes with increasing casting speed are identified: I) an isotropic domain‐like structure; II) unidirectionally aligned crystalline bands; and III) a corrugated dendritic morphology. Interestingly, increasing the solute concentration does not affect these morphologies but merely the associated transition velocities. Numerical simulation of both the fluid dynamics in the coating bead and the crystallization itself not only explains these morphological trends but also the decrease in the width of the crystalline bands of morphology II with the casting speed. They demonstrate that the latter provides an optimal processing window for organic field‐effect transistors, with minimized charge trapping, maximized on/off ratio, and reliability factor. [ABSTRACT FROM AUTHOR]

Self‐assembly of colloidal nanoparticles (NPs) is widely employed in nanofabrication to have regulated shape with fascinating functions. However, to have a specific desired shape at centimeter‐scale without template is challenging. Herein, by harnessing the colloidal nanoparticle thin film crack engineering, robust and highly transparent centimeter‐scale rods with uniform width and thickness are obtained. The dimension of these rods can be tailored via controlling the solvent composition, NPs volume fraction, and suspension descending rate. Their mechanical stiffness and elastic properties can be further improved by thermal annealing. It is demonstrated that these rods can be used as probes for surface enhanced Raman scattering detection making use of their rich nanostructured surface. This crack engineering strategy can be used as a universal method to assemble the nanoscale colloids into centimeter‐scale rods for analytical and photoelectrical applications. [ABSTRACT FROM AUTHOR]

Glasses are generally assumed to be isotropic and there are no literature reports of elastic anisotropy for molecular glasses. However, as glasses formed by physical vapor deposition can be structurally anisotropic, it is of interest to investigate the elastic anisotropy in these materials. Micro‐Brillouin light spectroscopy is used in several experimental geometries to determine the elastic stiffness tensors of three glass films of itraconazole vapor‐deposited at substrate temperatures (Tsub) of 330, 315, and 290 K, respectively. Significant elastic anisotropy is observed and, in these glasses, the elastic anisotropy shows a strong correlation with the molecular orientation. The out‐of‐plane and in‐plane Young's moduli of the high Tsub (330 K) sample, which features a predominantly vertical molecular orientation, exhibit a high anisotropy ratio of 2.2. The observed elastic anisotropy is much larger than those previously observed in liquid crystals and even many crystalline solids. [ABSTRACT FROM AUTHOR]

Cellular membranes have long served as an inspiration for nanomaterial research. The preparation of ultrathin polydopamine (PDA) films with integrated protein pores containing phospholipids and an embedded domain of a membrane protein glycophorin A as simplified cell membrane mimics is reported. Large area, ultrathin PDA films are obtained by electropolymerization on gold surfaces with 10–18 nm thickness and dimensions of up to 2.5 cm2. The films are transferred from gold to various other substrates such as nylon mesh, silicon, or substrates containing holes in the micrometer range, and they remain intact even after transfer. The novel transfer technique gives access to freestanding PDA films that remain stable even at the air interfaces with elastic moduli of ≈6–12 GPa, which are higher than any other PDA films reported before. As the PDA film thickness is within the range of cellular membranes, monodisperse protein nanopores, so‐called "nanodiscs," are integrated as functional entities. These nanodisc‐containing PDA films can serve as semi‐permeable films, in which the embedded pores control material transport. In the future, these simplified cell membrane mimics may offer structural investigations of the embedded membrane proteins to receive an improved understanding of protein‐mediated transport processes in cellular membranes. [ABSTRACT FROM AUTHOR]

Controlling thermomechanical anisotropy is important for emerging heat management applications such as thermal interface and electronic packaging materials. Whereas many studies report on thermal transport in anisotropic nanocomposite materials, a fundamental understanding of the interplay between mechanical and thermal properties is missing, due to the lack of measurements of direction‐dependent mechanical properties. In this work, exceptionally coherent and transparent hybrid Bragg stacks made of strictly alternating mica‐type nanosheets (synthetic hectorite) and polymer layers (polyvinylpyrrolidone) were fabricated at large scale. Distinct from ordinary nanocomposites, these stacks display long‐range periodicity, which is tunable down to angstrom precision. A large thermal transport anisotropy (up to 38) is consequently observed, with the high in‐plane thermal conductivity (up to 5.7 W m−1 K−1) exhibiting an effective medium behavior. The unique hybrid material combined with advanced characterization techniques allows correlating the full elastic tensors to the direction‐dependent thermal conductivities. We, therefore, provide a first analysis on how the direction‐dependent Young's and shear moduli influence the flow of heat. [ABSTRACT FROM AUTHOR]

A gel‐to‐crystal phase transition of a dipeptide supramolecular assembly mediates active water transportation in oils. The addition of water into ultrafast‐assembling dipeptide organogels can induce a lamellar‐to‐hexagonal structural transformation of dipeptide molecular arrangement. Consequently, a phase transition from gel to crystal occurs and in turn water is transported in the dipeptide crystal via well‐defined channels. On a macroscopic scale, water transport in the bulk system exhibits an anisotropic characteristic, which can be tuned by the presence of ions in the Hofmeister series. These favorable features enable the automatic separation of dispersed nanoparticles from dissolved electrolytes in aqueous solution. These findings demonstrate the potential of this assembled system for active filtration without external pressure. [ABSTRACT FROM AUTHOR]

We have previously described a number of lipophilic conformationally constrained spiro carbocyclic 2,6‐diketopiperazine (2,6‐DKP)‐1‐acetohydroxamic acids as potent antitrypanosomal agents. In this report, we extend the SAR analysis in this class of compounds with respect to in vitro growth inhibition of Trypanosoma and Leishmania parasites. Introduction of bulky hydrophobic substituents at the vicinal position of the basic nitrogen atom in the spiro carbocyclic 2,6‐DKP ring system can provide analogues which are potently active against bloodstream form Trypanosoma brucei and exhibit significant activities toward Trypanosoma cruzi epimastogotes and Leishmania infantum promastigotes and intracellular amastigotes. In particular, compounds possessing a benzyl or 4‐chlorobenzyl substituent were found to be the most active growth inhibitors, with activities in the low nanomolar and low micromolar ranges for T. brucei and L. infantum, respectively. The benzyl‐substituted (S)‐enantiomer was the most potent derivative against T. brucei (IC50 = 6.8 n m), T. cruzi (IC50 = 0.21 μ m), and L. infantum promastigotes (IC50 = 2.67 μ m) and intracellular amastigotes (IC50 = 2.60 μ m). Moreover, the (R)‐chiral benzyl‐substituted derivative and its racemic counterpart displayed significant activities against L. donovani. Importantly, the active compounds show high selectivity in comparison with two mammalian cell lines. [ABSTRACT FROM AUTHOR]

In our search to cluster as many phenylene units as possible in a given space, we have proceeded to the three-dimensional world of benzene-based molecules by employing covalently interlocked cyclohexa- m-phenylenes, as present in the unique paddlewheel-shaped polyphenylene 10. A precursor was conceived, in which freely rotating m-chlorophenylene units provide sufficient solubility along with the necessary proximity for the final ring closure to give 10. Monitoring the assembly of solubilized tert-butyl derivatives of 10 into supramolecular carbon nanostructures by dynamic light scattering (DLS) and Brillouin light scattering (BLS) revealed the dimensions of the initially formed aggregates as well as the amorphous character of the solid state. [ABSTRACT FROM AUTHOR]

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3,6-Connected cyclohexadienes as precursors for polyphenylenes are synthesized and characterized by mass spectrometry and NMR spectroscopy. Pure fractions of trimers, hexamers, and nonamers are collected after separation of the product mixture by recycling GPC. The anticipated formation of rigid linear structures, due to the trans-configuration of the monomeric units, is supported by density functional theory and experimentally confirmed by dynamic light scattering from dilute solution at low scattering angles. The obtained translational diffusion coefficients are represented by rigid rod-like or prolate ellipsoid-like molecular shapes. The measurements of diffusion coefficients reveal a length-dependent ratio of 1:2:3 between the three oligomers, which directly correlates to the expected length extension from trimer to nonamer. [ABSTRACT FROM AUTHOR]

The use of responsive thin hydrogel films as the active matrix in sensor applications requires detailed knowledge of their structural and dynamical properties and their responsiveness to external conditions. Here, the structure and dynamics in photo-crosslinked, surface-attached films (≈1 μm dry thickness) of a poly( N-isopropylacrylamide) (PNIPAAm)-based terpolymer (containing 5% methacrylic acid and 1% benzophenone methacrylate comonomers) at different temperatures and salt (NaCl) contents are reported. The swelling is monitored by surface plasmon resonance/optical waveguide spectroscopy (SPR/OWS), and the hydrogel dynamics are studied by micro-photon correlation spectroscopy. In addition to the expected volume phase transition above a critical temperature of ca. 32-35 °C and at NaCl concentrations above 1 m, SPR/OWS reveals subtle thickness variations at lower salt concentrations. The fast cooperative diffusion of the polymer network and a slow mode for the relaxation of the thermal concentration fluctuations in the grafted hydrogel layer exhibit a non-monotonic dependence on the salinity and a strong slowdown with temperature near the collapse transition. These dynamics respond sensitively and distinctly to structural changes induced by increasing temperature or added monovalent salt in comparison to the only subtle changes of the polymer fraction. [ABSTRACT FROM AUTHOR]

Extreme Elasticity Anisotropy: Extreme Elasticity Anisotropy in Molecular Glasses (Adv. Funct. Keywords: Brillouin light spectroscopy; elastic anisotropy; molecular glasses; orientation; vapor deposition EN Brillouin light spectroscopy elastic anisotropy molecular glasses orientation vapor deposition 1 1 1 06/06/20 20200604 NES 200604 In article number 2001481, Mark D. Ediger, George Fytas, and co-workers reveal the strong correlation between elastic anisotropy and molecular orientation in vapor-deposited organic glasses of rod-shaped itraconazole. Brillouin light spectroscopy, elastic anisotropy, molecular glasses, orientation, vapor deposition. [Extracted from the article]

In ihrem Forschungsartikel auf S. 1302 zeigen M. Retsch, J. Breu, G. Fytas et al., dass hierdurch eine beispiellose Periodizität zwischen den Ebenen und ein abstimmbares Confinement mit Angström-Präzision erreicht wird. In ihrem Forschungsartikel auf S. 1302 zeigen M. Retsch, J. Breu, G. Fytas et al., dass hierdurch eine beispiellose Periodizität zwischen den Ebenen und ein abstimmbares Confinement mit Angström-Präzision erreicht wird. Die selektive Synthese eines Porphyrin/Graphen-Nanoband-Hybrids auf einer Oberfläche sowie seine Charakterisierung werden von S. Decurtins, G. Bottari, R. Fasel, T. Torres et al. in ihrem Forschungsartikel auf S. 1350 beschrieben. [Extracted from the article]