Claudia Schmidt

The influence of the hydrophilicity of mesoporous silica on wetting with water was investigated by comparing a standard hydrophilic MCM‐41 and a partially hydrophobicized material obtained by trimethylsilylation of MCM‐41. The materials were characterized using X‐ray diffraction, N ₂ physisorption, thermogravimetric analysis, infrared spectroscopy, as well as ²⁹ Si and ¹³ C solid‐state nuclear magnetic resonance spectroscopy. Trimethylsilylation leads to a reduction of the pore diameter (determined using density functional theory) from 3.8 to 3.6 nm. Using proton solid‐state nuclear magnetic resonance (NMR) under magic‐angle spinning, it was found that the filling of these narrow pores with increasing amounts of water follows an axial mode, independent of surface hydrophilicity. The axial model of pore‐filling is supported by the coexistence of two characteristic ¹ H NMR water signals, one from physisorbed water molecules, which can exchange protons with silanol groups, and one from bulk‐like water in completely filled pores, where water molecules are in exchange between sites at the pore wall and sites closer to the center of the pore.

Porous nitrogen-doped carbons are promising for energy storage and gas adsorption, with performance governed by pore structure and surface chemistry. This study examines how hydrated alkali (LiCl, NaCl, KCl) and alkaline earth (MgCl2, CaCl2) metal chlorides affect the carbonization of molecular precursors (adenine, guanine, glucose) through templating and catalytic roles. Alkali chlorides largely preserve precursor composition and exhibit minimal templating, with NaCl being mostly inert. In contrast, alkaline earth chlorides strongly influence carbonization. MgCl2 functions as both template and catalyst, producing highly porous carbons with very high surface areas (up to 4648 m2/g) and modifying nitrogen configurations. CaCl2 primarily acts as a template, generating porosity while maintaining precursor chemistry. Precursor structure also matters: adenine forms tubular morphologies with MgCl2, unlike guanine. Electrochemical measurements reveal that MgCl2-derived carbons, particularly adenine-MgCl2, showed the best performance in supercapacitors (165 F/g) and Zn-ion capacitors (136 mA h/g) due to their high surface area, accessible microporosity and moderate nitrogen content. These results demonstrate that hydrated metal chlorides provide a simple strategy to tune the structure and chemistry of nitrogen-doped carbons through salt-assisted carbonization.

Hydrothermal carbonization of trehalose, in contrast to other saccharides, leads to the formation of microspheres with a bimodal size distribution. The microspheres develop hierarchical porosity with micro-, meso-, and macro-pores after pyrolysis.

Carbon suboxide (C₃O₂) is a unique molecule able to polymerize spontaneously into highly conjugated light‐absorbing structures at temperatures as low as 0 °C. Despite obvious advantages, little is known about the nature and the functional properties of this carbonaceous material. In this work, the aim is to bring “red carbon,” a forgotten polymeric semiconductor, back to the community's attention. A solution polymerization process is adapted to simplify the synthesis and control the structure. This allows one to obtain this crystalline covalent material at low temperatures. Both spectroscopic and elemental analyses support the chemical structure represented as conjugated ladder polypyrone ribbons. Density functional theory calculations suggest a crystalline structure of AB stacks of polypyrone ribbons and identify the material as a direct bandgap semiconductor with a medium bandgap that is further confirmed by optical analysis. The material shows promising photocatalytic performance using blue light. Moreover, the simple condensation–aromatization route described here allows the straightforward fabrication of conjugated ladder polymers and can be inspiring for the synthesis of carbonaceous materials at low temperatures in general.

Treatment of Na⁺-based hectorite LAPONITE® (LAP) and of Na⁺-montmorillonite (MMT) with a homologous series of γ-aminopropyl(methyl)_x(ethoxy)_ysilanes (x + y = 3, y > 0) in toluene was studied by means of thermogravimetric analysis coupled with mass spectrometry, infrared spectroscopy, ²⁹Si and ²³Na solid-state nuclear magnetic resonance spectroscopy and powder X-ray diffraction. The triethoxy silane (APTS) exclusively grafts on the clays' edges as branched oligomers whereas both the monoethoxy silane (APMS) and the diethoxy silane (APDS) are also intercalated, the latter as linear oligomers. Intercalation of APMS varies for MMT and LAP: MMT hosts the smallest amounts of the silanes with marginal increase of the basal distance and no stabilization of water. On the contrary, LAP accommodates the largest amount of guests in the form of monomeric APMS which yields the largest increase of the basal distance and stabilizes water up to 200 °C when APMS dimerizes. APMS stabilization is attributed to intramolecular Si–O–H–NH₂ hydrogen bonds and the hydrophobic geminal methyl groups together with the trimethylene sides of the cyclic monomers are thought to compartmentalize the hydrated sodium sites. The high temperature release of water from APMS@LAP is discussed in the light of potentially triggered interphase degradation in composite materials for recycling purposes.

Thermally stabilized and subsequently carbonized nanofibers are a promising material for many technical applications in fields such as tissue engineering or energy storage. They can be obtained from a variety of different polymer precursors via electrospinning. While some methods have been tested for post-carbonization doping of nanofibers with the desired ingredients, very little is known about carbonization of blend nanofibers from two or more polymeric precursors. In this paper, we report on the preparation, thermal treatment and resulting properties of poly(acrylonitrile) (PAN)/poly(vinylidene fluoride) (PVDF) blend nanofibers produced by wire-based electrospinning of binary polymer solutions. Using a wide variety of spectroscopic, microscopic and thermal characterization methods, the chemical and morphological transition during oxidative stabilization (280 °C) and incipient carbonization (500 °C) was thoroughly investigated. Both PAN and PVDF precursor polymers were detected and analyzed qualitatively and quantitatively during all stages of thermal treatment. Compared to pure PAN nanofibers, the blend nanofibers showed increased fiber diameters, strong reduction of undesired morphological changes during oxidative stabilization and increased conductivity after carbonization.