Search

Kunststoffe sind in unserem Alltag allgegenwärtig, und die Akkumulation von Kunststoffabfällen in unserer Umwelt stellt ein großes gesellschaftliches Problem dar. Daher sind Methoden für das Recycling von Kunststoffabfällen im Hinblick auf eine künftige Kreislaufwirtschaft von hohem Interesse. Insbesondere der Abbau von Polymeren nach Nutzung durch Verbraucher hin zu wertschöpfenden kleinen Molekülen stellt eine nachhaltige Strategie für eine Kohlenstoff‐Kreislaufwirtschaft dar. Trotz jüngster Fortschritte ist der chemische Polymerabbau nach wie vor weitgehend auf chemische Redox‐Reagenzien beschränkt oder durch eine geringe Energieeffizienz photochemischer Prozesse limitiert. In dieser Arbeit berichten wir über einen leistungsstarken eisenkatalysierten Abbau von Polystyrolen mit hohem Molekulargewicht durch Elektrochemie, um effizient monomere Benzoylprodukte zu liefern. Die Robustheit der Ferraelektrokatalyse wurde durch den Abbau von verschiedenen realen Nach‐Gebrauchs‐Kunststoffen, ebenfalls im Gramm‐Maßstab, bestätigt. Die kathodische Halbreaktion wurde weitgehend durch die Wasserstoffentwicklungsreaktion (HER) dargestellt. Der skalierbare elektrolytische Polymerabbau konnte ausschließlich mit Solarenergie über ein handelsübliches Solarpanel betrieben werden, was auf ein herausragendes Potenzial für eine dezentralisierte, grüne Wasserstoffwirtschaft hinweist. [ABSTRACT FROM AUTHOR]

Während Kunststoffe wie Polyethylenterephthalat (PET) bereits effizient durch die Aktivität von Hydrolasen abgebaut werden können, sind andere synthetische Polymere wie Polyurethane (PUs) und Polyamide (PAs) weitgehend resistent gegenüber einem biologischen Abbau. In dieser Studie lösten wir die erste Kristallstruktur der metagenomischen Urethanase UMG‐SP‐1, identifizierten hochflexible Loopregionen, die Reste des aktiven Zentrums enthalten, und untersuchten insgesamt 20 potenzielle Hotspots mittels Sättigungsmutagenese. Die durch Protein Engineering erzeugten Einzelmutanten wiesen eine fast 3‐ bzw. 8‐fach verbesserte Aktivität gegenüber hochstabilen N‐Arylurethan‐ und Amidbindungen auf. Darüber hinaus konnte die Freisetzung der entsprechenden Monomere aus einem thermoplastischen Polyester‐PU und einem PA (Nylon 6) durch die Aktivität einer einzigen, metagenomischen Urethanase nach kurzer Inkubationszeit nachgewiesen werden. Dadurch konnte das Hydrolyseprofil von UMG‐SP‐1 über die bekannten niedermolekularen Carbamate hinaus erweitert werden und erschließt so neue Möglichkeiten für den enzymatischen Abbau und das Recycling von Kunststoffen und Plastikabfällen. Damit unterstützt diese Studie Bemühungen um die Verbesserung einer Kreislaufwirtschaft für synthetische Polymere. [ABSTRACT FROM AUTHOR]

This article explores the field of nanomedicine and its potential applications in targeted drug delivery. It discusses the concept of "nanocarriers" that can transport drugs to specific organs and infected tissues, minimizing side effects. The article presents two experimental series that demonstrate the synthesis and loading of nanoparticles using polymers and various cargos. The experiments investigate the behavior of the nanoparticles in response to changes in pH, showing promising results for targeted drug delivery. The article highlights the educational opportunities and interdisciplinary connections that can be made through the teaching of nanomedicine in chemistry, biology, and physics classes. [Extracted from the article]

• Polymer desiccant wheel with high water uptake and low regeneration temperature is studied. • Polymer's adsorption capacity of 1.15 g kg−1 at 90 %RH is five times that of silica gel. • Polymer's desorption rate coefficient is 1.32–1.64 times that of silica gel at 40–70 °C heat sources. • The maximum ∆ Y and DCOP of the polymer desiccant wheel are 4.0 g kg−1 and 0.66, respectively. • Polymer desiccant wheel offers a promising measure for ultra-low dew point humidity control. Desiccant wheels have been widely used in humidity control, particularly under conditions with ultra-low dew point temperatures. However, traditional desiccants such as silica gel and zeolites are subject to relatively low adsorption capacity and high regeneration temperature. To address these challenges, a type of polymer material with high water uptake and low regeneration temperature is investigated in this paper. Firstly, the adsorption/desorption capacity of this polymer is thoroughly tested. Results reveal that its remarkable equilibrium adsorption capacity and desorption rate coefficients k LDF,de are 350% and 32–64% higher than that of silica gel, respectively. Moreover, its required regeneration temperature is just about 40–70 °C. The performance of the desiccant wheel using this polymer is simulated by a model validated by experiments tests. Parameter analysis demonstrates that the desiccant wheel is suitable for cool and humid conditions, reaching the maximum moisture removal (∆ Y) and dehumidification coefficient of performance (DCOP) of 4.0 g kg−1 and 0.66, respectively. Furthermore, the corresponding relationship between other parameters and the optimal rotation speed is discussed in detail. The ω opt is around 18 rph, enabling the attainment of the highest ∆ Y. Finally, the performance comparison with a traditional silica gel desiccant wheel is carried out. The results indicate that the polymer one performs 17–53.9% higher in terms of both ∆ Y and DCOP than the silica gel counterpart. And the most significant improvement is observed in low relative humidity conditions (45%RH), where ∆ Y and DCOP are 1.25–1.53 times that of the silica gel's, highlighting the advantageous utilization of the polymer material. [ABSTRACT FROM AUTHOR]

Summary SMPs took an impressive development since the 1990s until today. Within the market of elastic bonding and sealing they grew over‐proportionally and established themselves as an integral part. Primarily, the market was dominated by just one supplier but the field diversified over the last 20 years and other companies entered the market with own SMP‐prepolymer solutions or products. The SMPs developed from the construction industry into many different industrial branches due to their superior variability, easy handling, high tolerance against environmental influences and aesthetics. The most important applications are still found within the construction and DIY business but automotive, rail and equipment‐manufacturing applications for SMPs are catching up. [ABSTRACT FROM AUTHOR]

Proteine und Enzyme sind äußerst vielseitige Biomaterialien, die aufgrund ihrer hohen Spezifität für Rezeptoren und Substrate, ihrer Abbaubarkeit, geringen Toxizität und insgesamt guten Biokompatibilität hervorragend für ein breites Spektrum medizinischer Anwendungen geeignet sind. Durch die Anordnung mehrerer nativer oder modifizierter Proteine zu nanometergroßen Protein‐Nanopartikeln können zusätzliche vorteilhafte Eigenschaften wie eine erhöhte Stabilität im Blutstrom erreicht werden. In diesem Aufsatz konzentrieren wir uns auf künstliche Nanopartikelsysteme, bei denen Proteine das Hauptstrukturelement sind und nicht nur als eingeschlossene Wirkstoffe transportiert werden. Während unter natürlichen Bedingungen lediglich bestimmte Proteine definierte Aggregate und Nanopartikel bilden, können durch chemische Modifikationen oder Veränderungen in der physikalischen Umgebung Nanopartikel aus vielen verschiedenen globulären Proteinen und Enzymen hergestellt werden. Fortschritte bei den Herstellungsmethoden von proteinbasierten Nanopartikeln haben zu einer neuen Generation von Nanosystemen geführt, die über einfache Wirkstofftransporter hinausgehen und vielfältige Anwendungen ermöglichen, wie z.B. gezielte Arzneimittelabgabe, Theranostik, Nanokatalyse und Proteintherapie. [ABSTRACT FROM AUTHOR]

Copyright of Technisches Messen is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wir stellen ein Einzelkettennanopartikel (SCNP)‐System vor, welches bei identischer Konzentration die Photooxidation unpolarer Alkene bis zu dreimal effizienter katalysieren kann als ein äquivalenter niedermolekularer Photosensibilisator. Konkret haben wir SCNPs basierend auf Poly(ethylenglykol)methylethermethacrylat und Glycidylmethacrylat entwickelt, welches wir über multifunktionelle Thiol‐Epoxid‐Verknüpfungen in Kombination mit der Funktionalisierung mit Bengalrosa (RB) in einer Eintopfreaktion falten. Die SCNPs weisen sowohl eine hydrophile Hülle als auch hydrophobe photokatalytische Regionen auf. Die Photooxidation des innenliegenden Alkens der Ölsäure verläuft unter Einstrahlung von grünem Licht. Kovalent an die SCNPs gebundenes RB ist dreimal sensitiver gegenüber unpolaren Alkene als freies RB in Lösung. Dies ist unserer Hypothese nach auf die räumliche Nähe der photosensibilisierenden Gruppen zum Substrat in der hydrophoben Region zurückzuführen. Unser Ansatz zeigt, dass SCNP‐basierte Katalysatoren eine verbesserte Photokatalyse durch Einschränkungseffekte (confinement effects) in einer homogenen Reaktionsumgebung ermöglichen können. [ABSTRACT FROM AUTHOR]

Summary Within the repertoire of reactive, elastic bonding & sealing the Silane‐modified polymers exhibit a unique position. They show a very high structural diversity which is quite unique within the area of elastic joining technologies. This is due to the fact that a great variability of base polymers can be used for making SMPs and that there are different methods and ways known for introducing a silane group into these polymers. In the last years the range of accessible hybrid materials was further expanded and new products based on these entered the market. That further pushed the limits of this technology within the elastic bonding and sealing applications. In the second part of this series around SMPs we want to explore these applications of this versatile technology. [ABSTRACT FROM AUTHOR]

Für eine nachhaltige Kreislaufwirtschaft müssen Polymere auf rezyklierte und biobasierte Rohstoffe umgestellt werden, und sie müssen bezüglich der Emissionen CO2‐neutral werden. Dies gilt nicht nur für Strukturpolymere, z. B. in Verpackungen oder technischen Anwendungen, sondern auch für Funktionspolymere in flüssigen Formulierungen: in Klebstoffen oder Schmiermitteln, als Verdickungs‐ oder Dispersionsmittel. Am Ende ihrer Lebensdauer müssen Polymere entweder gesammelt und technisch rezykliert werden oder biologisch abbaubar sein, wenn sie nicht sammelbar sind. Fortschritte in der Polymerchemie, in Anwendungen und durch zunehmend rechnergestützte Methoden der Materialwissenschaft ermöglichen einen ganzheitlichen Ansatz: Polymere werden bereits für ihre Rezyklierbarkeit oder biologische Abbaubarkeit konzipiert. Dieser Aufsatz zeigt, wie neue wissenschaftliche Erkenntnisse in Verbindung mit entsprechenden rechtlichen, gesellschaftlichen und wirtschaftlichen Randbedingungen den Weg zu einer umfassenden Kreislaufwirtschaft für Polymere weisen können. [ABSTRACT FROM AUTHOR]

Copyright of Matériaux et Techniques is the property of EDP Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mechanophore sind molekulare Einheiten, die in Polymere eingebaut werden und auf Kraft mit konstitutionellen, konfigurativen oder konformationellen Bindungsumlagerungen reagieren, um Funktionalität zu ermöglichen. Bis heute wurden bereits einige chemisch latente Motive durch mechanochemische Methoden in Polymeren aktiviert, aber die Erzeugung sekundärer Amine blieb unerforscht. Hier berichten wir über Carbamoyloxime als mechanochemische Schutzgruppen für sekundäre Amine. Wir zeigen, dass Carbamoyloxime eine kraftinduzierte homolytische Bindungsspaltung an der N−O‐Oximbindung in Polymeren eingehen und so das freie Amin erzeugen. Die Reaktion verläuft analog zu ihrem photochemischen Gegenstück über Carbamoyloxyl‐ und Aminylradikale. Schließlich wenden wir das Carbamoyloxim‐Motiv in einer kraftaktivierten organokatalytischen Knoevenagel‐Reaktion an. Wir glauben, dass diese Schutzgruppenstrategie universell für viele andere sekundäre und primäre Amine in Polymermaterialien angewendet werden kann. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is a widely seen neurodegenerative condition recognized by misfolded α-synuclein (αSyn) protein, a prominent indicator for PD and other synucleinopathies. Motor symptoms like stiffness, akinesia, rest tremor, and postural instability coexist with nonmotor symptoms that differ from person to person in the development of PD. These symptoms arise from a progressive loss of synapses and neurons, leading to a widespread degenerative process in multiple organs. Implementing medical and surgical interventions, such as deep brain stimulation, has enhanced individuals' overall well-being and long-term survival with PD. It should be mentioned that these treatments cannot stop the condition from getting worse. The complicated structure of the brain and the existence of a semi-permeable barrier, commonly known as the BBB, have traditionally made medication delivery for the treatment of PD a challenging endeavor. The drug's low lipophilic nature, enormous size, and peculiarity for various ATP-dependent transport mechanisms hinder its ability to enter brain cells. This article delves at the potential of drug delivery systems based on chitosan (CS) to treat PD., (Copyright © 2024 Académie Nationale de Pharmacie. Published by Elsevier Masson SAS. All rights reserved.)

Summary Polymers play versatile roles in the pandemic. They range from personal protective equipment with goggles and visors made of polyethylene terephthalate (PET) and polycarbonate (PC), to mouth‐nose coverings with inner layers of fine, melt‐blown polypropylene fleece, and finally to swabs made of polystyrene and nylon or viscose that are used in diagnostics. BioNTech/Pfizer and Moderna's mRNA vaccines, which were the first to be approved as corona vaccines in Europe, are based on sequence‐defined polyanions, which can easily and rapidly be produced and adapted to occurring virus mutations. Consequently, there will be no quick end to the pandemic without the use of polymers. Polymers are not only indispensable in this pandemic in personal protective equipment, diagnostics and ultimately in therapy. The research in antiviral materials that was spurred during the COVID‐19 pandemic may position us well for future pandemics. Self‐sterilizing masks are already commercially available and, because they are reusable, have the advantage of requiring far fewer masks to be procured than is the case with disposable masks. This could avoid future mask shortages. Antiviral surface coatings, which can be activated by external stimuli such as sunlight, can help to reduce the viral load on frequently touched surfaces and help to prevent virus transmission. In addition, peptide‐polymer conjugates offer the opportunity to further optimize mRNA vaccines. Because these conjugates can be tailored to target immune cells, they reduce the risk of allergic reactions and side effects, which in turn could result in greater acceptance in the population and increase the willingness to get vaccinated. [ABSTRACT FROM AUTHOR]

When tunnelling with a TBM (Tunnel Boring Machine) in rock and soil, mostly the machine is described and often reduced to a slogan. Such descriptions say little about geotechnical processes at the tunnel face that are key to the success of tunnel driving and must be considered when selecting a tunnelling system. In soil tunnels the tunnel face must be safely supported and extracting material must be possible. For a slurry shield the slurry must not escape and pressure must act on the face. In the literature mostly bentonite content is considered. With an Earth‐Pressure balance machine the soil has to have characteristics that it can be remoulded and transformed in a mass of adequate consistency with mechanical means, adding water and additives such that this mass can support the face and be extracted. Long‐term experience shows that the fine content and polymers are also important factors. Flow channels (pores) in open gravel may be clogged, and the face supported by seepage forces. Also, the drag forces in the slurry circuit are increased and the operation of the slurry circuit became more stable. Rates of advance exceeding 10 m/day were achieved with a 11.6 m slurry shield. The limited depth of penetration of the slurry could be determined in‐situ. For fine‐grained soils the characteristics of the fines are crucial and are described by the Atterberg limits. Soil mechanics strength properties may be vastly different. [ABSTRACT FROM AUTHOR]

Copyright of Tribologie und Schmierungstechnik is the property of Narr Francke Attempto Verlag GmbH & Co.KG and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Vitrimere sind kovalent vernetzte Polymere, die ihre Netzwerktopologie durch aktivierbaren assoziativen Bindungsaustausch neu organisieren können, wenn die Topologie‐Einfriertemperatur (Tv) überschritten wird. Trotz zahlreicher entwickelter Vitrimersysteme besteht ein gravierender Mangel an Methoden für eine kontrollierte und ortsaufgelöste Aktivierung des Bindungsaustauschs oberhalb der Tv. Hier präsentieren wir ein Konzept, das die lokale Freisetzung des effizienten Umesterungskatalysators 1,5,7‐Triazabicyclo[4.4.0]dec‐5‐en (TBD) durch UV‐induzierte Spaltung einer photolatenten Base in einem kovalent vernetzten Thiol‐Epoxid‐Polymer ermöglicht. Mittels Spannungsrelaxationsmessungen, die weit über der Tv des Netzwerks durchgeführt wurden, konnte gezeigt werden, dass nur die kontrollierte Freisetzung von TBD Umesterungen und die damit verbundene Relaxation der Netzwerkspannung ermöglicht. Zudem konnte durch lokal induzierte permanente Formänderungen im Material eine ortsaufgelöste UV‐vermittelte Photoaktivierung der vitrimeren Eigenschaften demonstriert werden. [ABSTRACT FROM AUTHOR]

Supramolekulare Koordinationskäfige zeigen ein breites Spektrum an nützlichen Eigenschaften, wie zum Beispiel komplexe maschinenartige Operationen, Katalyse in deren nanoskopischen Hohlräumen und umfangreiche Wirt‐Gast‐Chemie. Hier berichten wir über die Aufnahme und Freisetzung von nichtkovalent verkapselter, pharmazeutischer Fracht aus einem oktaedrischen Pd‐Käfig, welcher an jedem Vertex Polymerketten trägt. Sechs Poly(ethylenglykol)‐dekorierte Bipyridinliganden werden verwendet, um einen oktaedrischen PdII6(TPT)4‐Käfig zu bilden. Der entstandene supramolekulare Wirt verkapselt Progesteron und Ibuprofen in seiner hydrophoben Nanokavität. Der Käfig wird mittels Scherkräfte aktiviert, die durch Ultraschall in wässriger Lösung erzeugt werden und zu einer vollständigen Freisetzung der Fracht bei Bindungsbruch führen, wie NMR‐ und GPC‐Analysen zeigen. [ABSTRACT FROM AUTHOR]

Der Bruch von Polymermaterialien ist ein multiskaliger Prozess, der mit der Spaltung einer einzelnen molekularen Bindung beginnt und sich bis zu einer Bruchstelle im Festkörper ausbreitet. Die Quantifizierung der während dieses Prozesses gebrochenen Bindungen bleibt eine große Herausforderung, würde aber helfen, die Verteilung und Dissipation makroskopischer mechanischer Energie zu verstehen. Wir zeigen hier die Gestaltung und die Synthese von fluorogenen molekularen optischen Kraftsonden (Mechanofluorophoren), die das gesamte sichtbare Spektrum sowohl in Absorption als auch in Emission abdecken. Ihre dual‐fluoreszenten Eigenschaften ermöglichen es, nicht gebrochene und gebrochene Bindungen in gelösten Polymeren und im Festkörper durch Fluoreszenzspektroskopie und ‐mikroskopie zu verfolgen. Wichtig ist, dass wir einen Ansatz entwickeln, um die absolute Anzahl und den relativen Anteil von intakten und gebrochenen Bindungen mit hoher lokaler Auflösung zu bestimmen. Wir gehen davon aus, dass unsere Mechanofluorophore in Kombination mit unserer Quantifizierungsmethodik eine quantitative Beschreibung von Versagensprozessen in Materialien von weichen Hydrogelen bis hin zu Hochleistungspolymeren ermöglichen werden. [ABSTRACT FROM AUTHOR]

Wood has numerous advantages: It is sustainable, has a good CO2 and energy balance, is environmentally friendly due to its biodegradability, and its mechanical properties are so good that it is used as a building material, e.g. for multilevel houses. Moreover, thanks to modern research, obvious disadvantages of wood compared to other materials can now be improved by chemical modifications: Chemically modified wood has a higher durability and does not swell or shrink as much as natural wood upon changing environmental conditions. Therefore, besides bio‐based plastics or wood‐plastic composites, chemically modified wood might contribute to more sustainability as well as climate and environmental protection in the future.This article presents fundamentals of the hierarchical structure and chemical modification of wood and curriculum‐related experiments that provide insights into current research on this topic and is suitable to teach aspects of polymer chemistry in the context of sustainability and climate protection at school or in a student laboratory. [ABSTRACT FROM AUTHOR]

Wood has numerous advantages: It is sustainable, has a good CO2 and energy balance, is environmentally friendly due to its biodegradability, and its mechanical properties are so good that it is used as a building material, e.g. for multilevel houses. Moreover, thanks to modern research, obvious disadvantages of wood compared to other materials can now be improved by chemical modifications: Chemically modified wood has a higher durability and does not swell or shrink as much as natural wood upon changing environmental conditions. Therefore, besides bio‐based plastics or wood‐plastic composites, chemically modified wood might contribute to more sustainability as well as climate and environmental protection in the future.This article presents fundamentals of the hierarchical structure and chemical modification of wood and curriculum‐related experiments that provide insights into current research on this topic and is suitable to teach aspects of polymer chemistry in the context of sustainability and climate protection at school or in a student laboratory. [ABSTRACT FROM AUTHOR]

Copyright of Tribologie und Schmierungstechnik is the property of Narr Francke Attempto Verlag GmbH & Co.KG and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Developed the ab initio and MD model for refrigerant-lubricant oil system. • Obtained intermolecular interactions from atomic and electronic level. • Characterized solubility properties, solvation mechanism and structure. Hydrofluoroolefins (HFO) are considered as substitute to HFC refrigerant in the Organic Rankine cycle, however, the lack of studies on HFO refrigerant-lubricant mixtures hampers their further applications. This reported computational work aims to provide guidance for the development of suitable lubricants for new refrigerants. We use ab initio and large scale molecular dynamics (MD) modeling to gain insight into the molecular mechanism of interaction between polypropylene glycol dimethyl ether (PPGDE) and R1233zd(E). The ab initio calculated stable structures, interaction energies and charge distribution analysis indicate that the oxygen atoms in PPGDE and chlorine atom in R1233zd(E) play a major role in the solubility, the calculated interaction energy is -13.97 kJ mol−1 for the most stable configuration; The MD simulated density of R1233zd(E) agrees well with experimental data over a wide range of temperatures and pressures, the obtained cohesive energy density, solubility parameter, Flory−Huggins parameter and radial distribution functions (RDF) allow a characterization of the solubility properties and reveal the solvation mechanism and structure as well, PPGDE molecules begin to be attached to the Cl atoms in R1233zd(E) from the first neighbor shell of radius 2.925 Å. [ABSTRACT FROM AUTHOR]

A rhodium‐based multicomponent catalytic system for well‐controlled living polymerization of phenylacetylenes has been developed. The catalytic system is composed of readily available and bench‐stable [Rh(nbd)Cl]2, aryl boronic acid derivatives, diphenylacetylene, 50 % aqueous KOH, and PPh3. This system offers a method for the facile and versatile synthesis of various end‐functionalized cis‐stereoregular poly(phenylacetylene)s because components from aryl boronic acids and diphenylacetylene were introduced to the initiating end of the polymers. The polymerization reaction shows a typical living nature with a high initiation efficiency, and the molecular weight of the resulting poly(phenylacetylene)s can be readily controlled with very narrow molecular‐weight distributions (Mw/Mn=1.02–1.09). The experimental results suggest that the present catalytic system has a higher polymerization activity than the polymerization activities of other rhodium‐based catalytic systems previously reported. [ABSTRACT FROM AUTHOR]

The electrochemical splitting of water holds promise for the storage of energy produced intermittently by renewable energy sources. The evolution of hydrogen currently relies on the use of platinum as a catalyst—which is scarce and expensive—and ongoing research is focused towards finding cheaper alternatives. In this context, 2D polymers grown as single layers on surfaces have emerged as porous materials with tunable chemical and electronic structures that can be used for improving the catalytic activity of metal surfaces. Here, we use designed organic molecules to fabricate covalent 2D architectures by an Ullmann‐type coupling reaction on Au(111). The polymer‐patterned gold electrode exhibits a hydrogen evolution reaction activity up to three times higher than that of bare gold. Through rational design of the polymer on the molecular level we engineered hydrogen evolution activity by an approach that can be easily extended to other electrocatalytic reactions. [ABSTRACT FROM AUTHOR]

Bacterial polyhydroxyalkanoates (PHAs) are a unique class of biodegradable polymers because of their biodegradability in ambient environments and structural diversity enabled by side‐chain groups. However, the biosynthesis of PHAs is slow and expensive, limiting their broader applications as commodity plastics. To overcome such limitation, the catalyzed chemical synthesis of bacterial PHAs has been developed, using the metal‐catalyzed stereoselective ring‐opening (co)polymerization of racemic cyclic diolides (rac‐8DLR, R=alkyl group). In this combined experimental and computational study, polymerization kinetics, stereocontrol, copolymerization characteristics, and the properties of the resulting PHAs have been examined. Most notably, stereoselective copolymerizations of rac‐8DLMe with rac‐8DLR (R=Et, Bu) have yielded high‐molecular‐weight, crystalline isotactic PHA copolymers that are hard, ductile, and tough plastics, and exhibit polyolefin‐like thermal and mechanical properties. [ABSTRACT FROM AUTHOR]

While poly(acyclic orthoester)s (PAOEs) have many appealing features for drug delivery, their application is significantly hindered by a lack of facile synthetic methods. Reported here is a simple method for synthesizing acyclic diketene acetal monomers from diols and vinyl ether, and their polymerization with a diol to first synthesize PAOEs. The PAOEs rapidly hydrolyze at lysosomal pH. With the help of a cationic lipid, ovalbumin, a model vaccine antigen was efficiently loaded into PAOEs nanoparticles using a double emulsion method. These nanoparticles efficiently delivered ovalbumin into the cytosol of dendritic cells and demonstrated enhanced antigen presentation over poly(lactic‐co‐glycolic acid) (PLGA) nanoparticles. PAOEs are promising vehicles for intracellular delivery of biopharmaceuticals and could increase the utility of poly(orthoesters) in biomedical research. [ABSTRACT FROM AUTHOR]

2D polymer sheets with six positively charged pyrylium groups at each pore edge in a stacked single crystal can be transformed into a 2D polymer with six pyridines per pore by exposure to gaseous ammonia. This reaction furnishes still a crystalline material with tunable protonation degree at regular nano‐sized pores promising as separation membrane. The exfoliation is compared for both 2D polymers with the latter being superior. Its liquid phase exfoliation yields nanosheet dispersions, which can be size‐selected using centrifugation cascades. Monolayer contents of ≈30 % are achieved with ≈130 nm sized sheets in mg quantities, corresponding to tens of trillions of monolayers. Quantification of nanosheet sizes, layer number and mass shows that this exfoliation is comparable to graphite. Thus, we expect that recent advances in exfoliation of graphite or inorganic crystals (e.g. scale‐up, printing etc.) can be directly applied to this 2D polymer as well as to covalent organic frameworks. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) are highly modular porous crystalline polymers that are of interest for applications such as charge‐storage devices, nanofiltration membranes, and optoelectronic devices. COFs are typically synthesized as microcrystalline powders, which limits their performance in these applications, and their limited solubility precludes large‐scale processing into more useful morphologies and devices. We report a general, scalable method to exfoliate two‐dimensional imine‐linked COF powders by temporarily protonating their linkages. The resulting suspensions were cast into continuous crystalline COF films up to 10 cm in diameter, with thicknesses ranging from 50 nm to 20 μm depending on the suspension composition, concentration, and casting protocol. Furthermore, we demonstrate that the film fabrication process proceeds through a partial depolymerization/repolymerization mechanism, providing mechanically robust films that can be easily separated from their substrates. [ABSTRACT FROM AUTHOR]

Polymernetzwerke sind Materialien, die aus vielen kleineren Komponenten aufgebaut sind, die als "Vernetzungspunkte" und "Stränge" bezeichnet werden und über kovalente oder nichtkovalente/supramolekulare Wechselwirkungen miteinander verknüpft sind. Sie gehören zu den vielseitigsten, am häufigsten eingesetzten und wichtigsten Materialien. Von den ersten kommerziellen Polymeren über die Kunststoffrevolution des 20. Jahrhunderts bis in die Gegenwart gibt es nahezu keine Aspekte des modernen Lebens, die nicht von Polymernetzwerken beeinflusst werden. Dennoch müssen noch viele Herausforderungen in Angriff genommen werden, um ein vollständiges Verständnis dieser Materialien zu ermöglichen und ihre Entwicklung für künftige Anwendungen zu fördern, die von Energie‐Harvesting und Energiespeicherung bis zur Gewebezüchtung und additiven Fertigung reichen. Hier geben wir einen Überblick über die Grundlagen der Synthese, Struktur und Eigenschaften von Polymernetzwerken, unter Einbeziehung aktueller Trends auf dem Gebiet. Wir werden außerdem die neuesten Fortschritte bei der Anwendung des Moleküldesigns und der Steuerung der Topologie aufzeigen, um zu demonstrieren, wie ein tiefgehendes Verständnis der Struktur‐Eigenschaft‐Beziehungen zu hochentwickelten Netzwerken mit außergewöhnlichen Eigenschaften führen kann. [ABSTRACT FROM AUTHOR]

The ability to harness cellular redox processes for abiotic synthesis might allow the preparation of engineered hybrid living systems. Towards this goal we describe a new bacteria‐mediated iron‐catalysed reversible deactivation radical polymerisation (RDRP), with a range of metal‐chelating agents and monomers that can be used under ambient conditions with a bacterial redox initiation step to generate polymers. Cupriavidus metallidurans, Escherichia coli, and Clostridium sporogenes species were chosen for their redox enzyme systems and evaluated for their ability to induce polymer formation. Parameters including cell and catalyst concentration, initiator species, and monomer type were investigated. Water‐soluble synthetic polymers were produced in the presence of the bacteria with full preservation of cell viability. This method provides a means by which bacterial redox systems can be exploited to generate "unnatural" polymers in the presence of "host" cells, thus setting up the possibility of making natural–synthetic hybrid structures and conjugates. [ABSTRACT FROM AUTHOR]

Arbitrary shape (re)programming is appealing for fabricating untethered shape‐morphing photo‐actuators with intricate configurations and features. We present re‐programmable light‐responsive thermoplastic actuators with arbitrary initial shapes through spray‐coating of polyethylene terephthalate (PET) with an azobenzene‐doped light‐responsive liquid crystal network (LCN). The initial geometry of the actuator is controlled by thermally shaping and fixing the thermoplastic PET, allowing arbitrary shapes, including origami‐like folds and left‐ and right‐handed helicity within a single sample. The thermally fixed geometries can be reversibly actuated through light exposure, with fast, reversible area‐specific actuation such as winding, unwinding and unfolding. By shape re‐programming, the same sample can be re‐designed and light‐actuated again. The strategy presented here demonstrates easy fabrication of mechanically robust, recyclable, photo‐responsive actuators with highly tuneable geometries and actuation modes. [ABSTRACT FROM AUTHOR]

Crosslinked polymers (CLPs) exhibit exceptional mechanical properties as well as good chemical and solvent resistance. However, their reprocessing, recycling, and modification remain difficult. One promising approach to overcome this limitation is to introduce dynamic covalent bonds that enable chain‐exchange reactions and network‐structure rearrangements in identical polymer networks (A–A fusion), resulting in self‐healing and reprocessing properties. Reported here is the fusion of two distinct polymer networks (A–B fusion) by the dynamic behavior of bis(2,2,6,6‐tetramethylpiperidin‐1‐yl)disulfide (BiTEMPS) at the interface between different CLPs. The appearance, swelling behavior, and mechanical properties of the fused samples indicate exchange reactions of the BiTEMPS units and the formation of topological bonds at the interface, commensurate with the generation of a CLP that exhibits tunable properties. [ABSTRACT FROM AUTHOR]

Imprinting nanopatterns on flexible substrates has diverse applications in advanced fabrication. However, the traditional thermal nanoimprint lithography (T‐NIL) often causes shrinkage upon cooling. Here, a simple yet versatile method is introduced to fabricate multiple nanopatterns on a flexible substrate coated with an azopolymer by combining athermal nanoimprint lithography (AT‐NIL) and photolithography. The azopolymer has various mechanical properties upon photoirradiation: 1) phototunable glass‐transition temperatures (Tg) and concomitantly photoinduced switch from glassy plastic to viscoplastic polymer; 2) prominent modulation of viscoplasticity under light illumination at different wavelengths. Regionally selective multiple nanopatterns are conveniently fabricated, presenting angle‐dependent structural color images on poly(ethylene terephthalate) (PET) substrates. The flexible, athermal and multiple nanopatterning method has the potential for on‐demand fabrication of complex nanopatterns. [ABSTRACT FROM AUTHOR]

In various nickel(II) salicylaldiminato ethylene polymerization catalysts, which are a versatile mechanistic probe for substituent effects, longer perfluoroalkyl groups exert a strong effect on catalytic activities and polymer microstructures compared to the trifluoromethyl group. This effect is accounted for by a reduced electron density on the active sites, and is also supported by electrochemical studies. Thus, β‐hydride elimination, the key step of chain transfer and branching pathways, is disfavored while chain‐growth rates are enhanced. This enhancement occurs to an extent that enables living polymerizations in aqueous systems to afford ultra‐high‐molecular‐weight polyethylene for various chelating salicylaldimine motifs. These findings are mechanistically instructive as well as practically useful for illustrating the potential of perfluoroalkyl groups in catalyst design. [ABSTRACT FROM AUTHOR]

Polyphosphate (PolyP) is one of the most compact inorganic polyanionic biopolymers that participates in various physiological processes. However, the mechanism of the interaction between polyP and proteins remains poorly understood. Herein, we report that polyP can interact with positively charged green fluorescent protein, +36GFP, resulting in liquid–liquid phase separation (LLPS) by intermolecular electrostatic interactions in cells. Upon nutrient deprivation, genetically engineered Citrobacter freundii accumulates intracellular polyP at a rate of 210 μm min−1, resulting in the compartmentation of +36GFP at the cell poles within 1 h. Medium chain‐length polyP (60‐mer) could induce the formation of +36GFP coacervates in vitro at a protein concentration as low as 200 nm, which is of the same magnitude as native proteins. In contrast, shorter polyP (14‐mer) could not induce LLPS under the same conditions. This may offer a general approach to manipulate protein–protein interactions through LLPS. [ABSTRACT FROM AUTHOR]

Constructing a solid electrolyte interface (SEI) is a highly effective approach to overcome the poor reversibility of lithium (Li) metal anodes. Herein, an adhesive and self‐healable supramolecular copolymer, comprising of pendant poly(ethylene oxide) (PEO) segments and ureido‐pyrimidinone (UPy) quadruple‐hydrogen‐bonding moieties, is developed as a protection layer of Li anode by a simple drop‐coating. The protection performance of in‐situ‐formed LiPEO–UPy SEI layer is significantly enhanced owing to the strong binding and improved stability arising from a spontaneous reaction between UPy groups and Li metal. An ultrathin (approximately 70 nm) LiPEO–UPy layer can contribute to stable and dendrite‐free cycling at a high areal capacity of 10 mAh cm−2 at 5 mA cm−2 for 1000 h. This coating together with the promising electrochemical performance offers a new strategy for the development of dendrite‐free metal anodes. [ABSTRACT FROM AUTHOR]

RNA‐based therapies offer a wide range of therapeutic interventions including the treatment of skin diseases; however, the strategies to efficiently deliver these biomolecules are still limited due to obstacles related to the cellular uptake and cytoplasmic delivery. Herein, we report the synthesis of a triggerable polymeric nanoparticle (NP) library composed of 160 formulations, presenting physico‐chemical diversity and differential responsiveness to light. Six formulations were more efficient (up to 500 %) than commercially available lipofectamine in gene‐knockdown activity. These formulations showed differential internalization by skin cells and the endosomal escape was rapid (minutes range). The NPs were effective in the release of siRNA and miRNA. Acute skin wounds treated with the top hit NP complexed with miRNA‐150‐5p healed faster than wounds treated with scrambled miRNA. Light‐activatable NPs offer a new strategy to topically deliver non‐coding RNAs. [ABSTRACT FROM AUTHOR]

Based on a "TADF + Linker" strategy (TADF=thermally activated delayed fluorescence), demonstrated here is the successful construction of conjugated polymers that allow highly efficient delayed fluorescence. Small molecular TADF blocks are linked together using a methyl‐substituted phenylene linker to form polymers. With the growing number of methyl groups on the phenylene, the energy level of the local excited triplet state (3LEb) from the delocalized polymer backbone gradually increases, and finally surpasses the charge‐transfer triplet state (3CT). As a result, the diminished delayed fluorescence can be recovered for the tetramethyl phenylene containing polymer, revealing a record‐high external quantum efficiency (EQE) of 23.5 % (68.8 cd A−1, 60.0 lm W−1) and Commission Internationale de l′Eclairage (CIE) coordinates of (0.25, 0.52). Combined with an orange‐red TADF emitter, a bright white electroluminescence is also obtained with a peak EQE of 20.9 % (61.1 cd A−1, 56.4 lm W−1) and CIE coordinates of (0.36, 0.51). [ABSTRACT FROM AUTHOR]