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Herein, we synthesized a series of siloxane-based poly(ionic liquid)s (PILs) with imidazolium-type species in the main chain via the multicomponent Debus–Radziszewski reaction. We employed oligodimethylsiloxane diamine precursors to integrate flexible spacers in the polymer backbone and ultimately succeeded in obtaining main-chain PILs with low glass transition temperatures (Tgs) in the range of −40 to −18 °C. Such PILs were combined with conventional hydrophobic vinylimidazolium-based PILs for the fabrication of porous membranes via interpolyelectrolyte complexation with poly(acrylic acid), which leads to enhanced mechanical performance in the tensile testing measurements. This study will enrich the structure library of main-chain PILs and open up more opportunities for potential industrial applications of porous imidazolium-based membranes. published

Herein, we report a simple and versatile synthetic approach towards siloxane-based poly(ionic liquid)s (PILs) with unusually low glass transition temperatures (Tg) down to −73°C, and thus “liquid-like” behavior at room temperature. We designed a polydimethylsiloxane-derived copolymer carrying dialkylimidazolium moieties, and by careful selection of the side-chain length and the type of anions we were able to manipulate its Tg over a wide range and reach high ionic conductivities (σDC) up to 4.8 × 10−5 S/cm at 300 K. The ionized species make up only a minor fraction (

Herewith, we report a straightforward, experimentally simple, and environmentally benign synthetic strategy toward cyclocondensation polymers. Using a fully aromatic polyimide as model system, we d...

A simple route for the in-situ orientation of carbon nanofillers applied during the curing process of a carbon fiber reinforced polymer (CRFP) in a hot press, is demonstrated. Neat MWCNT, amine-functionalized MWCNT (MWCNT-NH2) and CNF were dispersed in an epoxy resin using a three-roll-mill (TRM) to ensure good dispersion. The process leads to a hierarchically structured functional composite where MWCNT/CNF are aligned in the z-direction (out-of-plane) of the carbon fiber plies, giving rise to improved mechanical and electrical performance. Our results demonstrate that aligned carbon nanofillers yield significantly more pronounced improvements than non-oriented fillers. An applicable processing route towards advanced functional composite materials with major practical importance is presented in this study.

The pursuit of CO2 reduction targets has increased the need of storage capacities for renewable energy or thermal energy to enhance the efficiency of industrial processes. To combine the benefits of latent and sensible thermal energy storage systems, the concept of micro encapsulated phase change material is presented. The microparticles are designed to work in a high-temperature thermal energy storage system considering economic and technical points of view. Therefore, particles of sodium nitrate are physio-mechanical coated with polyimide by using spray-drying in a fluidized bed reactor. To evaluate the influence of the process conditions, several coating experiments with different process settings are performed. Afterward, the samples are analyzed to determine their properties. Besides a microscopic and a sieving analysis, they are tested in the laboratory to define their mechanical and thermal limits. Finally, a rough layout of a thermal energy storage system using the produced particles is presented and compared to a common sensible thermal energy storage.

Here, the hydrothermal synthesis (HTS) of 2,3‐diarylquinoxalines from 1,2‐diketones and o‐phenylendiamines (o‐PDAs) was achieved. The synthesis is simple, fast, and generates high yields, without requiring any organic solvents, strong acids or toxic catalysts. Reaction times down to 90 % in all cases). Moreover, it was shown that HTS has high compatibility: (i) hydrochlorides, a standard commercial form of amines, could be used directly as combined amine source and acidic catalyst, and (ii) Boc‐diprotected o‐PDA could be directly employed as substrate that underwent HT deprotection. A systematic large‐scale computational comparison of all reported syntheses of the presented quinoxalines from the same starting compounds showed that this method is more environmentally friendly and less toxic than all existing methods and revealed generic synthetic routes for improving reaction yields. Finally, the application of the synthesized compounds as fluorescent dyes for cell staining was explored., In hot water: 2,3‐Diarylquinoxalines and biquinoxalines are synthesized in a rapid, efficient and green fashion in nothing but high‐temperature water. Through a large‐scale computational analysis, the herein reported reaction conditions are compared with all reported syntheses of the presented compounds.

In this work, a novel class of fully organic, lightweight composite materials was prepared by incorporating highly crystalline, hydrothermally synthesized poly(p-phenylene pyromellitimide) (PPPI) microparticles into a commercial epoxy matrix. Particle loadings of up to 15 vol% could be achieved. Microstructural, mechanical, and thermal properties of these composites were investigated by scanning electron microscopy, three-point bending and Vickers hardness testing, dynamic mechanical analysis, nanoindentation, and thermogravimetric analysis. The incorporation of the PPPI filler particles into the epoxy matrix was found to be homogeneous. Powder X-ray diffraction shows that PPPI's crystallinity is retained in the composites, and infrared spectroscopy indicates a covalent bonding of PPPI to the epoxy matrix. Flexural modulus and storage modulus were increased by the PPPI addition, while the flexural strain at break was reduced. In contrast to that, the flexural strength remained unaffected by the incorporation of PPPI filler particles. Raising the filler content also resulted in an improvement of hardness. Furthermore, a decrease in glass-transition temperature with increasing PPPI content was observed, as well as a pronounced increase in thermal stability of the composites in comparison to the unfilled cured epoxy resin. These results indicate the high potential of this new class of composites with prospective applicability e.g. in the fields of sports equipment, aerospace, and automotive technology. published

Biogenic metal oxides (MxOy) feature structures as highly functional and unique as the organisms generating them. They have caught the attention of scientists for the development of novel materials by biomimicry. In order to understand how biogenic MxOy could inspire novel technologies, we have reviewed examples of all biogenic MxOy, as well as the current state of understanding of the interactions between the inorganic MxOy and the biological matter they originate from and are connected to. In this review, we first summarize the origins of the precursors that living nature converts into MxOy. From the point-of-view of our materials chemists, we present an overview of the biogenesis of silica, iron and manganese oxides, as the only reported biogenic MxOy to date. These MxOy are found across all five kingdoms (bacteria, protoctista, fungi, plants and animals). We discuss the key molecules involved in the biosynthesis of MxOy, the functionality of the MxOy structures, and the techniques by which the biogenic MxOy can be studied. We close by outlining the biomimetic approaches inspired by biogenic MxOy materials and their challenges, and we point at promising directions for future organic-inorganic materials and their synthesis. published

Carbon fiber reinforced polymers (CFRPs) are promising composite materials for high-performance and lightweight applications, gaining increasing interest in aerospace and automotive industries. Epoxy thermosets are frequently used as polymer matrices of CFRPs, which are usually responsible for failure of the composite. In this work different types of carbon nanotubes (CNTs) and carbon nanofibers (CNF) are added to the epoxy resin to improve mechanical properties of the whole CFRP composite. The dispersion of the fillers on a three-roll mill (TRM) is shown comparing their dispersion behavior in the resin. Results of increased modulus and strength of the hierarchical composite in four-point bending tests are presented.

International audience; The year 2020 marks the 100th anniversary of the first article on poly merization, published by Hermann Staudinger. It is Staudinger who realized that polymers consist of long chains of covalently linked building blocks. Polymers have had a tremendous impact on the society ever since this initial publication. People live in a world that is almost impossible to imagine without synthetic polymers. But what does the future hold for polymer science? In this article, the editors and advisory board of Macromolecular Chemistry and Physics reflect on this question.

Verschiedene Polyimide und Polyamide wurden in letzter Zeit durch hydrothermale Synthese in nichts als H2O unter Hochdruck- und Hochtemperaturbedingungen hergestellt. Keines dieser Polymere weist jedoch ein konjugiertes Polymerrückgrat auf. Hiermit berichten wir über eine Erweiterung des synthetischen Anwendungsbereichs dieser einfachen und von Natur aus umweltfreundlichen Polymerisationstechnik auf die Herstellung von konjugierten Polymeren. Ausgewählte Vertreter von zwei verschiedenen Polymerklassen, Pyrronpolymere und Polybenzimidazole, wurden hydrothermal synthetisiert. Neben einer mechanistischen Diskussion der Polymerbildung wird auch eine elektrochemische Charakterisierung des vielversprechendsten Produktes präsentiert. published

High-purity, symmetrically substituted perylene and naphthalene bisimides were obtained by hydrothermal condensation of monoamines with the corresponding bisanhydride. The hydrothermal imidization proceeds quantitatively, without the need for organic solvents, catalysts or excess of the amines. published

Poly(p-phenylene vinylene)s (PPVs) have been studied for decades, but research on this interesting class of conjugated polymers is far from being completed. New applications like in bioimaging keep emerging and even simple structural variations are still waiting to be explored. Surprisingly, not even dithioalkyl-substituted PPVs (S-PPVs) have been reported in the peer-reviewed literature, although the corresponding dialkoxy-substituted PPVs (O-PPVs) like MEH-PPV or MDMO-PPV are most frequently used and although thioalkyl substituents can improve the material properties significantly. We herein report the development of a highly efficient, scalable two-step synthesis of Gilch monomers for S-PPVs starting from low-cost 1,4-diiodobenzene. A low-temperature polymerization protocol has been developed for these monomers, affording high-molecular weight S-PPVs in excellent yields. The thermal, electrochemical, and photophysical properties of S-PPVs are reported to highlight the potential of these polymers. Furthermore, treatment with dimethyldioxirane is demonstrated to result in rapid conversion into sulfone-substituted PPVs (SO2-PPVs), introducing a route to high-molecular weight SO2-PPVs with exceptional stability and solid-state photoluminescence quantum yields of up to 0.46.

Carbon nanotubes (CNT) provide an outstanding property spectrum which can be used to improve a wide range of materials. However, the transfer of properties from the nanoscale to a macroscopic material is a limiting factor. Different approaches of functionalizing the surface of a CNT can improve the interaction with the surrounding matrix but is connected to difficult and expensive treatments, which are usually inconvenient for industrial applications. Here, a simple and eco-friendly method is presented for the oxidation of CNT, where hydrogen peroxide (H2O2) is the only chemical needed and no toxic emissions are released. Also, the extensive step of the incorporation of CNT to an epoxy matrix is simplified to an ultrasonic dispersion in the liquid hardener component. The effectiveness is proven by mechanical tests of produced CNT/CFRP and compared to a conventional processing route. The combination of those simple and cost efficient strategies can be utilized to produce multiscale composites with improved mechanical performance in an ecological and economical way.

The term “inorganic–organic hybrid materials” designates inorganic building blocks in the colloidal domain (1–1000 nm) embedded in an organic, typically polymeric, matrix. Owing to their outstanding properties, hybrid materials have the potential to improve human life significantly. In the last two decades, the importance of reorienting chemical syntheses in the direction of more sustainable, less harmful and energy-consuming procedures, referred to as green chemistry, has been much emphasized and worked on. This review deals with the application of green chemistry to the synthesis of inorganic–organic hybrid materials. The origin and preparation both of the inorganic components and of the organic polymer matrix are critically analyzed for various examples. The development of more sustainable syntheses for hybrid materials still poses an open challenge. Potential options to tackle this task are discussed.

Hydrothermal polymerization (HTP) is a technique to synthesize highly crystalline polyimides in solely water. The process involves monomer salt intermediates also able to undergo other polymerizations during the HTP experiment: sub-hydrothermal polymerization (sHTP) and solid-state polycondensation (SSP). Both processes yield semicrystalline polyimides at best. This is widely believed to result from irreversible bond-formation and the incorporation of conformational defects during chain growth. Here, microwave-assisted HTP is used, allowing for controlling the heating time to the reaction temperature, and thus to strongly reduce sHTP. Moreover, we show that highest crystallinity can be obtained in the higher hydrothermal regime (≈200 °C), and synthesize two polyimides of sufficient crystallinity to refine their crystal structures from powder X-ray diffraction data. This study brings us one step closer to a general picture and rational design of the hydrothermal synthesis of polyimides.

Hydrothermal polymerization (HTP) is a benign and inherently green synthetic approach to synthesize highly crystalline polyimides (PIs) in nothing but high-temperature water (HTW). In a typical HTP experiment, highly crystalline PI microparticles of sheet-like as well as flower-like morphology are obtained. Within this contribution, the effect of four additives (PEG400, PEG8000, P123, CTAB) on the crystallinity and morphology of the PI poly(p-phenylene pyromellitimide) is investigated. From the experiments performed, it becomes evident that the type as well as the concentration of additive heavily influences morphology. However, even the highest tested concentration of additive (67 g L−1 of PEG8000) does not lead to a change in average crystallinity, as determined from powder X-ray diffraction. Hence, this approach provides a straightforward method to intentionally tune PI particle morphology without losing the outstanding materials properties generated by the high crystallinity obtained via HTP. Additionally, a hypothesis regarding the poly(ethylene glycol)-induced morphology alteration is presented. published

In hot water: Hydrothermal crystallization was recently used to transform amporphous polymer networks into amide-linked, stable covalent-organic frameworks. This work is highlighted in the context of the synthesis and especially crystallization of organic materials by using high-temperature water.

'Extreme biomimetics' and 'geomimetics' are relatively recent fields of materials chemistry. Both take inspiration from natural materials for generating novel synthetic materials or enhanced properties in known materials. In geomimetics, the source of inspiration is geological systems, while extreme biomimetics is motivated by organisms operating in-from an anthropocentric point of view-extreme conditions. This review article focuses on geomimetic and extreme biomimetic hydrothermal synthesis. Since hydrothermal preparative chemistry typically uses nothing but water and the required precursors, the field belongs to the research area of 'green materials chemistry'. Geomimetics, on the one hand, takes inspiration from natural materials formation. Extreme Biomimetics, on the other hand, is inspired by materials found in extremophile organisms, instead of aiming to implement their actual biosynthesis. In this contribution, both extreme biomimetics and geomimetics are first defined, and further critically discussed on the basis of recent, selected examples. Moreover, the necessity for the two closely related fields as well their prospects are commented on. published

Inorganic–organic hybrid materials allow for combining features typical of the inorganic component with those of the organic component in one material. Generally, the preparation of organic and inorganic compounds requires considerably different synthesis conditions. Hence, the development of one-pot routes to inorganic–organic hybrid materials is challenging. We herein report a fully green one-pot synthesis of polyimide/silica (PI/SiO2) hybrids. Specifically, we co-condense both components hydrothermally, using nothing but the respective precursors and water. Furthermore, we show that the PI and the SiO2 component can be covalently connected under hydrothermal conditions, using the compatibilizer (3-aminopropyl)-triethoxysilane. We thoroughly investigate the effect of different reaction conditions, including temperature, pH, precursor concentration and reaction time on the morphology and crystallinity of the final materials. The polyimide component, poly(hexamethylene pyromellitimide) was chosen for its thermoplasticity, which allows for processing both the PI and the PI/SiO2via sintering. For being a solvent-free method, sintering qualifies as a green processing technique. This work is the first report of the simultaneous hydrothermal condensation of an inorganic and an organic material. published

Vitrimers, strong organic glass formers, are covalent networks that are able to change their topology through thermoactivated bond exchange reactions. At high temperatures, vitrimers can flow and behave like viscoelastic liquids. At low temperatures, exchange reactions are very long and vitrimers behave like classical thermosets. The transition from the liquid to the solid is reversible and is, in fact, a glass transition. By changing the content and nature of the catalyst, we can tune the transesterification reaction rate and show that the vitrimer glass transition temperature and the broadness of the transition can be controlled at will in epoxy-based vitrimers. This opens new possibilities in practical applications of thermosets such as healing or convenient processability in a wide temperature range.

A mechanistic study regarding the synthesis of aromatic polyimides (PIs) under hydrothermal conditions is presented. We demonstrate evidence that the first step of the reaction is the formation of a nylon type salt, which can be isolated. Upon heating the salt in the presence of water at 180 °C, polyimides are formed from the salts. Additionally performed DFT calculations substantiate the experimental findings and give evidence that the formation of imides is energetically favorable in hot water. The intermediate salts as well as the resulting PIs are characterized by diverse analytical techniques (SEC, FT-IR, WAXS, SEM). By selective fractionation, it is possible to obtain polyimides of moderate to high molecular weights that form tough films. The polymerization mechanism is discussed, and it is shown that different loci of reaction are possible, namely interfacial polycondensation, heterophase polymerization and topochemical transformations, which seem to occur in parallel. Finally, poloxamers can be used as additives for the fine-tuning of the polymer morphology.