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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...

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

Various polyimides and polyamides have recently been prepared via hydrothermal synthesis in nothing but H2O under high‐pressure and high‐temperature conditions. However, none of the prepared polymers feature a truly conjugated polymer backbone. Here, we report on an expansion of the synthetic scope of this straightforward and inherently environmentally friendly polymerization technique to the generation of conjugated polymers. Selected representatives of two different polymer classes, pyrrone polymers and polybenzimidazoles, were generated hydrothermally. We present a mechanistic discussion of the polymer formation process as well as an electrochemical characterization of the most promising product., In hot water: The scope of hydrothermal polymerization has been expanded. Pyrrone polymers and polybenzimidazoles can now be generated in high‐temperature water by a straightforward one‐step synthesis.

Hochkondensierte, vollständig konjugierte aromatische Verbindungen sind interessante Kandidaten zur Anwendung in organischer Elektronik. Mit steigender Kristallinität verbessern sich ihre elektronischen Eigenschaften. Hier wird gezeigt, dass die Kristallisation von drei Archetypen solcher Moleküle – Pentacentetron, Indigo und Perinon – hydrothermal erreicht werden kann. Dieser Befund ist angesichts der Strukturen dieser Verbindungen höchst erstaunlich. Darüber hinaus wird gezeigt, dass Perinon ausgehend von Naphthalinbisanhydrid und o-Phenylendiamin in ausschließlich hochtemperiertem Wasser und ohne Zusatz von Cosolventien oder Katalysatoren hergestellt werden kann. Weiterhin kann die Transformation durch den Einsatz von Mikrowellen-Strahlung drastisch beschleunigt werden. Dies ist der erste Bericht über die hydrothermale Herstellung von zwei kondensierten Heterocyclen. published

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

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.

Highly fused, fully conjugated aromatic compounds are interesting candidates for organic electronics. With higher crystallinity their electronic properties improve. It is shown here that the crystallization of three archetypes of such molecules-pentacenetetrone, indigo, and perinone-can be achieved hydrothermally. Given their molecular structure, this is a truly startling finding. In addition, it is demonstrated that perinone can also be synthesized in solely high-temperature water from the starting compounds naphthalene bisanhydride and o-phenylene diamine without the need for co-solvents or catalysts. The transformation can be drastically accelerated by the application of microwave irradiation. This is the first report on the hydrothermal generation of two fused heterocycles. published

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