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Bio-inspired V2O5–polymer hybrid films were prepared following a one-step self-organization procedure based on liquid crystal formation of organic and inorganic components. These materials were previously reported to exhibit advantageous mechanical properties, comparable to biomaterials, such as human bone and dentin. Here, we show that these hybrid films prepared via a fast and simple synthesis procedure have an additional function as an electrochromic material, exhibiting a long-term cycle stability under alternating potentials. The structures were found to remain intact without visible changes after more than hundred switching cycles and storing the devices for several weeks. Consequently, this multifunctional V2O5–polymer hybrid system shows great promise for various technical applications. [ABSTRACT FROM AUTHOR]

A small series of copoly(α,l-glutamic acid/dl-allylglycine)s with the same chain length and allylglycine content (∼10 mol %) but different spatial distribution of allylglycine units was synthesized and subsequently glycosylated via thiol-ene chemistry. Dilute aqueous copolypeptide solutions (0.1 wt %, physiological saline) were analyzed by circular dichroism spectroscopy, dynamic light scattering, and cryogenic transmission electron microscopy. The copolypeptides adopted a random coil or α-helix conformation, depending on solution pH, and the glycosylated residues either distorted or enhanced the folding into an α-helix depending on their location and spatial distribution along the chain. However, regardless of their secondary structure and degree of charging, all partially glycosylated copolypeptides self-assembled into 3D spherical structures, supposedly driven by a hydrophilic effect promoting microphase separation into glucose-rich and glutamate-rich domains.

Elemental sulfur, a waste product of the oil refinement process, represents a promising raw material for the synthesis of degradable polymers. We show that simple lithium alkoxides facilitate the polymerisation of elemental sulfur S 8 with industrially relevant propylene oxide (PO) and CS 2 (a base chemical sourced from waste S 8 itself) to give poly(monothiocarbonate-alt-S x ) in which x can be controlled by the amount of supplied sulfur. The in situ generation of thiolate intermediates obtained by a rearrangement, which follows CS 2 and PO incorporation, allows to combine S 8 and epoxides into one polymer sequence that would otherwise not be possible. Mechanistic investigations reveal that alkyl oligosulfide intermediates from S 8 ring opening and sulfur chain length equilibration represent the better nucleophiles for inserting the next PO if compared to the trithiocarbonates obtained from the competing CS 2 addition, which causes the sequence selectivity. The polymers can be crosslinked in situ with multifunctional thiols to yield reprocessable and degradable networks. Our report demonstrates how mechanistic understanding allows to combine intrinsically incompatible building blocks for sulfur waste utilisation., (© 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

Metal oxide-based photoelectrodes for solar water splitting often utilize nanostructures to increase the solid-liquid interface area. This reduces charge transport distances and increases the photocurrent for materials with short minority charge carrier diffusion lengths. While the merits of nanostructuring are well established, the effect of surface order on the photocurrent and carrier recombination has not yet received much attention in the literature. To evaluate the impact of pore ordering on the photoelectrochemical properties, mesoporous CuFe 2 O 4 (CFO) thin film photoanodes were prepared by dip-coating and soft-templating. Here, the pore order and geometry can be controlled by addition of copolymer surfactants poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic® F-127), polyisobutylene-block-poly(ethylene oxide) (PIB-PEO) and poly(ethylene-co-butylene)-block-poly(ethylene oxide) (Kraton liquid™-PEO, KLE). The non-ordered CFO showed the highest photocurrent density of 0.2 mA/cm 2 at 1.3 V vs. RHE for sulfite oxidation, but the least photocurrent density for water oxidation. Conversely, the ordered CFO presented the best photoelectrochemical water oxidation performance. These differences can be understood on the basis of the high surface area, which promotes hole transfer to sulfite (a fast hole acceptor), but retards oxidation of water (a slow hole acceptor) due to electron-hole recombination at the defective surface. This interpretation is confirmed by intensity-modulated photocurrent (IMPS) and vibrating Kelvin probe surface photovoltage spectroscopy (VKP-SPS). The lowest surface recombination rate was observed for the ordered KLE-based mesoporous CFO, which retains spherical pore shapes at the surface resulting in fewer surface defects. Overall, this work shows that the photoelectrochemical energy conversion efficiency of copper ferrite thin films is not just controlled by the surface area, but also by surface order., (© 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Inspired by mussel proteins that enable surface binding in harsh marine environments, we envisioned a platform of protein-repellent macromolecules based on poly(2-ethyl-2-oxazoline) carrying catechol and cationic functional groups. To facilitate surface attachment, catechol units were installed by copolymerizing a functional comonomer, i.e ., 2-(3,4-dimethoxyphenyl)-2-oxazoline, in a gradient fashion. Cationic units were introduced by partial acidic hydrolysis. The surface affinity of these polymers was probed using a quartz crystal microbalance with dissipation monitoring (QCM-D), and it was found that polymers with catechol units had a strong tendency to form surface-bound layers on different substrates, i.e ., gold, iron, borosilicate, and polystyrene. While the neutral catechol-containing polymers showed strong, but uncontrolled binding, the ones with additional cationic units were able to form defined and durable polymer films. These coatings were able to prevent the attachment of different model proteins, i.e ., bovine serum albumin (BSA), fibrinogen (FI), or lysozyme (LYZ). The herein-introduced platform offers straightforward access to nonfouling surface coatings using a biomimetic approach.

The novel material class of high entropy oxides with their unique and unexpected physicochemical properties is a candidate for energy applications. Herein, it is reported for the first time about the physico- and (photo-) electrochemical properties of ordered mesoporous (CoNiCuZnMg)Fe 2 O 4 thin films synthesized by a soft-templating and dip-coating approach. The A-site high entropy ferrites (HEF) are composed of periodically ordered mesopores building a highly accessible inorganic nanoarchitecture with large specific surface areas. The mesoporous spinel HEF thin films are found to be phase-pure and crack-free on the meso- and macroscale. The formation of the spinel structure hosting six distinct cations is verified by X-ray-based characterization techniques. Photoelectron spectroscopy gives insight into the chemical state of the implemented transition metals supporting the structural characterization data. Applied as photoanode for photoelectrochemical water splitting, the HEFs are photostable over several hours but show only low photoconductivity owing to fast surface recombination, as evidenced by intensity-modulated photocurrent spectroscopy. When applied as oxygen evolution reaction electrocatalyst, the HEF thin films possess overpotentials of 420 mV at 10 mA cm -2 in 1 m KOH. The results imply that the increase of the compositional disorder enhances the electronic transport properties, which are beneficial for both energy applications., (© 2023 The Authors. Small published by Wiley-VCH GmbH.)

We investigated changes in the hydration state of poly(ethylene glycol) (PEG) through morphological changes in Langmuir monolayers of a PEG-poly(l-lactide) (PlLA) (PEG- b -PlLA) diblock copolymer. When the PEG blocks were hydrated, we observed a remarkable morphology of bundles of ring-like filaments, arranged concentrically, yielding densely packed disk-like objects with a hollow center. We attribute the uniform curvature of these filaments to a strong mismatch between the molecular volumes occupied by PlLA blocks and hydrated PEG blocks. Under the constraint that each hydrated PEG block is attached to a hydrophobic PlLA block anchored to the air-water interface, this mismatch of molecular volumes caused strong repulsion within the PEG layer, in particular when the PlLA blocks packed tightly. Induced by a transition in the ordering of the PlLA blocks, the PEG blocks lost their hydration shell and packed into a dense polymer brush, accompanied by a reduction of the pressure within the PEG layer. During this packing process, the curvature of the filaments was eliminated and the ring-like filaments fractured into small linear pieces. Upon compression, the linear pieces coalesced and formed long filaments aligned in parallel. Importantly, upon expansion of the Langmuir film, these changes in morphology were reversible, and the PEG blocks could be rehydrated and bundles of concentrically arranged ring-like filaments were reformed. We conclude that the change in curvature of the filaments provides a means for distinguishing between the hydrated and dehydrated states of PEG.

Dark field scattering microscopy can create large hyperspectral data sets that contain a wealth of information on the properties and the molecular environment of noble metal nanoparticles. For a quick screening of samples of microscopic dimensions that contain many different types of plasmonic nanostructures, we propose a multivariate analysis of data sets of thousands to several hundreds of thousands of scattering spectra. By using non-negative matrix factorization for decomposing the spectra, components are identified that represent individual plasmon resonances and relative contributions of these resonances to particular microscopic focal volumes in the mapping data sets. Using data from silver and gold nanoparticles in the presence of different molecules, including gold nanoparticle-protein agglomerates or silver nanoparticles forming aggregates in the presence of acrylamide, plasmonic properties are observed that differ from those of the original nanoparticles. For the case of acrylamide, we show that the plasmon resonances of the silver nanoparticles are ideally suited to support surface enhanced Raman scattering (SERS) and the two-photon excited process of surface enhanced hyper Raman scattering (SEHRS). Both vibrational tools give complementary information on the in situ formed polyacrylamide and the molecular composition at the nanoparticle surface.

Post-polymerization modification provides an elegant way to introduce chemical functionalities onto macromolecules to produce tailor-made materials with superior properties. This concept was adapted to well-defined block copolymers of the poly(2-oxazoline) family and demonstrated the large potential of these macromolecules as universal toolkit for numerous applications. Triblock copolymers with separated water-soluble, alkyne- and alkene-containing segments were synthesized and orthogonally modified with various low-molecular weight functional molecules by copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) and thiol-ene (TE) click reactions, respectively. Representative toolkit polymers were used for the synthesis of gold, iron oxide and silica nanoparticles., (© 2021 The Authors. Published by Wiley-VCH GmbH.)

This opinion article describes recent approaches to use the "biorefinery" concept to lower the carbon footprint of typical mass polymers, by replacing parts of the fossil monomers with similar or even the same monomer made from regrowing dendritic biomass. Herein, the new and green catalytic synthetic routes are for lactic acid (LA), isosorbide (IS), 2,5-furandicarboxylic acid (FDCA), and p-xylene (pXL). Furthermore, the synthesis of two unconventional lignocellulosic biomass derivable monomers, i.e., α-methylene-γ-valerolactone (MeGVL) and levoglucosenol (LG), are presented. All those have the potential to enter in a cost-effective way, also the mass market and thereby recover lost areas for polymer materials. The differences of catalytic unit operations of the biorefinery are also discussed and the challenges that must be addressed along the synthesis path of each monomers., (© 2020 The Authors. Macromolecular Rapid Communications published by Wiley-VCH GmbH.)

Focusing on the phase-coexistence region in Langmuir films of poly(l-lactide), we investigated changes in nonequilibrated morphologies and the corresponding features of the isotherms induced by different experimental pathways of lateral compression and expansion. In this coexistence region, the surface pressure Π was larger than the expected equilibrium value and was found to increase upon compression, i.e., exhibited a nonhorizontal plateau. As shown earlier by using microscopic techniques [ Langmuir 2019 , 35 , 6129-6136], in this plateau region, well-ordered mesoscopic clusters coexisted with a surrounding matrix phase. We succeeded in reducing Π either by slowing down the rate of compression or through increasing the waiting time after stopping the movement of the barriers, which allowed for relaxations in the coexistence region. Intriguingly, the most significant pressure reduction was observed when recompressing a film that had already been compressed and expanded, if the recompression was started from an area value smaller than the one anticipated for the onset of the coexistence region. This observation suggests a "self-seeding" behavior, i.e., pre-existing nuclei allowed to circumvent the nucleation step. The decrease in Π was accompanied by a transformation of the initially formed metastable mesoscopic clusters into a thermodynamically favored filamentary morphology. Our results demonstrate that it is practically impossible to obtain fully equilibrated coexisting phases in a Langmuir polymer film, neither under conditions of extremely slow continuous compression nor for long waiting times at a constant area in the coexistence region which allow for reorganization.

A series of phenolic-acid-based 2-oxazoline monomers with methoxy-substituted phenyl and cinnamyl side chains is synthesized and polymerized in a microwave reactor at 140 °C using methyl tosylate as the initiator. The obtained poly(2-oxazoline)s are characterized by NMR spectroscopy, MALDI-TOF mass spectrometry, and size-exclusion chromatography (SEC). Kinetic studies reveal that the microwave-assisted polymerization is fast and completed within less than ≈10 min for low monomer-to-initiator ratios of ≤25. Polymers with number-average molar masses of up to 6500 g mol -1 and low dispersity (1.2-1.3) are produced. The aryl methyl ethers are successfully cleaved with aluminum triiodide/N,N'-diisopropylcarbodiimide to give a poly(2-oxazoline) with pendent catechol groups., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The unsaturated bicyclic acetal levoglucosenyl methyl ether was readily obtained from sustainable feedstock (cellulose) and polymerized by cationic ring-opening polymerization to produce a semicrystalline thermoplastic unsaturated polyacetal with relatively high apparent molar mass (up to ca. 36 kg mol -1 ) and decent dispersity (ca. 1.4). The double bonds along the chain can undergo hydrogenation and thiol-ene reactions as well as crosslinking, thus making this polyacetal potentially interesting as a reactive functional material., (© 2019 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

A one-step moderate energy vibrational emulsification method was successfully employed to produce thermo-responsive olive/silicone-based Janus emulsions stabilized by poly( N , N -diethylacrylamide) carrying 0.7 mol% oleoyl side chains. Completely engulfed emulsion droplets remained stable at room temperature and could be destabilized on demand upon heating to the transition temperature of the polymeric stabilizer. Time-dependent light micrographs demonstrate the temperature-induced breakdown of the Janus droplets, which opens new aspects of application, for instance in biocatalysis., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The readily available cellulose-derived bicyclic compound levoglucosenol was polymerized through ring-opening metathesis polymerization (ROMP) to yield polylevoglucosenol as a novel type of biomass-derived thermoplastic polyacetal, which, unlike polysaccharides, contains cyclic as well as linear segments in its main chain. High-molar-mass polyacetals with apparent weight-average molar masses of up to 100 kg mol -1 and dispersities of approximately 2 were produced despite the non-living/controlled character of the polymerization due to irreversible deactivation or termination of the catalyst/active chain ends. The resulting highly functionalized polyacetals are glassy in bulk with a glass transition temperature of around 100 °C. In analogy to polysaccharides, polylevoglucosenol degrades slowly in an acidic environment., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We studied morphological changes in a quasi-two-dimensional Langmuir film of low molar mass poly(l-lactide) upon increasing the surface density, starting from randomly distributed molecules to a homogeneous monolayer of closely packed molecules, followed by nucleation and growth of mesoscopic, three-dimensional clusters from an overcompressed monolayer. The corresponding nucleation density of mesoscopic clusters within the monolayer can be tailored through variation of the rate of compression. For a given surface density and temperature, the nucleation probability was found to increase linearly with the rate of compression, allowing to adjust the density of mesoscopic clusters over nearly 2 orders of magnitude.