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.

Herewith, we report a straightforward, experimentally simple, and environmentally benign synthetic strategy toward cyclocondensation polymers. Using a fully aromatic polyimide as model system, we demonstrate that products of extraordinary crystallinity can be generated in various protic, polar solvents (ethanol, iso-propyl alcohol, and glycerine) as well as in their mixtures with H2O via solvothermal polymerization. Depending on the type of solvent and the employed solvent composition, respectively, several physicochemical solvent properties (density, viscosity, polarity, and ionic product) can be intentionally adjusted to generate a plethora of morphologically different microparticlespartly with highly ordered structures down to the nanorangewhile maintaining full crystallinity. The method developed here is a highly valuable addition to the to date rather limited number of synthetic approaches toward high-performance polyimides and, as we believe, for cyclocondensation polymers in general.

Herein, we report a simple and versatile synthetic approach towards siloxanebased poly(ionic liquid)s (PILs) with unusually low glass transition temperatures (T g ) down to À73 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 T g over a wide range and reach high ionic conductivities (σ DC ) up to 4.8 Â 10 À5 S/cm at 300 K. The ionized species make up only a minor fraction (<25 mol%) of the overall repeating units and are supposedly randomly distributed: Yet our results indicate dramatic effects on the thermal properties due to repulsive interactions between ionic and non-ionic segments.

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