FUNCTIONALIZATION OF THE SURFACE OF HYPERCROSSLINKED POLYSTYRENE FOR CATALYST SYNTHESIS

Нанесенные наноразмерные катализаторы широко используются в различных процессах химической технологии. При этом особые требования предъявляются к носителю, используемому при синтезе катализаторов. Сверхсшитые полимеры являются перспективными носителями, однако зачастую не имеют требуемых свойств (например, кислотности). Для придания дополнительных свойств возможно модифицировать поверхность полимеров различными веществами или функциональными группами. В данной работе проведено исследование способов модификации и веществ-предшественников кремнийсодержащей фазы для модификации поверхности сверхсшитого полистирола диоксидом кремния. The supported nano-scale catalysts are widely used in different fields of chemical engineering. For the catalysts, the certain requirements are specified fort the catalyst supports. Hypercrosslinked polymers seem to be the prospective materials for the catalyst synthesis. However, polymeric matrices often do not meet some standards for catalyst supports (i.e. polymers are inert materials and do not have the acidic or basic properties). To infuse the additional properties to polymers it is possible to modify its surface with different compounds or functional groups. In this work, the study of the ways for the modification of the surface of hypercrosslinked polystyrene and silica-phase precursors was carried out.

Enhancing Heat Resistance of Red Color by Coating Fe2O3 Nanoparticles with Mesostructured Silica

The surface of α-Fe2O3 nanoparticles was successfully coated with mesostructured silica templated by surfactant assemblies using cetyltrimethylammonium ions. By repeating the coating operation, it was possible to control the thickness of the mesostructured silica phase. In the sample obtained with ten coatings, in particular, the aggregation and sintering of the α-Fe2O3 nanoparticles was suppressed, and the bright red before the heat treatment was maintained even after a heat treatment at 1300 °C.

n-Octadecane/Fumed Silica Phase Change Composite as Building Envelope for High Energy Efficiency

A novel n-octadecane/fumed silica phase change composite has been prepared as a building envelope with a high content of phase change material and improved energy efficiency. With a high porosity (88 vol%), the fumed silica provided sufficient space to impregnate a high quantity of n-octadecane (70 wt%). The composite exhibited high latent heat storage capacity (155.8 J/g), high crystallization fraction (96.5%), and a melting temperature of 26.76 °C close to that of pure n-octadecane. A 200 accelerated thermal cycle test confirmed good thermal reliability and chemical stability of the phase change composite. The thermal conductivity of n-octadecane was reduced by 34% after impregnation in fumed silica. A phase change composite panel was fabricated and compared to a commercial polystyrene foam panel. When used as the roof of a test room, the phase change composite panel more efficiently retarded heat transfer from a halogen lamp to the room and delayed the increase in the indoor temperature than that by the polystyrene panel. The indoor temperatures of the room with the phase change composite panel roof were 19.8 and 22.9 °C, while those with the polystyrene panel roof were 29.9 and 31.9 °C at 2200 and 9000 s after lamp illumination.

Solid-state NMR spectroscopic studies of 13C,15N,29Si-enriched biosilica from the marine diatom Cyclotella cryptica

Diatoms are algae producing micro- and nano-structured cell walls mainly containing amorphous silica. The shape and patterning of these cell walls is species-specific. Herein, the biosilica of Cyclotella cryptica, a centric marine diatom with a massive organic matrix, is studied. Solid-state NMR spectroscopy is applied to gain deeper insight into the interactions at the organic–inorganic interface of the cell walls. The various organic compounds like polysaccharides as well as proteins and long-chain polyamines (LCPAs) are detected by observation of heteronuclei like 13C and 15N whereas the silica phase is studied using 29Si NMR spectroscopy. The sensitivity of the NMR experiments is strongly enhanced by isotope-labeling of the diatoms during cultivation with 13C, 15N and 29Si. The presence of two different chitin species in the biosilica is demonstrated. This observation is supported by a monosaccharide analysis of the silica-associated organic matrix where a high amount of glucosamine is found. Moreover, the Rotational Echo Double Resonance (REDOR) experiment provides distance information for heteronuclear spins. 13C{29Si} REDOR experiments reveal proximities between different organic compounds and the silica phase. The closest contacts between silica and organic compounds appear for different signals in the 13C-chemical shift range of 40–60 ppm, the typical range for LCPAs.

Solid-state NMR spectroscopic studies of 13C,15N,29Si-enriched biosilica from the marine diatom Cyclotella cryptica

Diatoms are algae producing micro- and nano-structured cell walls mainly containing amorphous silica. The shape and patterning of these cell walls is species-specific. Herein, the biosilica of Cyclotella cryptica, a centric marine diatom with a massive organic matrix, is studied. Solid-state NMR spectroscopy is applied to gain deeper insight into the interactions at the organic-inorganic interface of the cell walls. The various organic compounds like polysaccharides as well as proteins and long-chain polyamines (LCPAs) are detected by observation of heteronuclei like 13C and 15N whereas the silica phase is studied using 29Si NMR spectroscopy. The sensitivity of the NMR experiments is strongly enhanced by isotope-labeling of the diatoms during cultivation with 13C, 15N and 29Si. The presence of two different chitin species in the biosilica is demonstrated. This observation is supported by a monosaccharide analysis of the silica-associated organic matrix where a high amount of glucosamine is found. Moreover, the Rotational Echo Double Resonance (REDOR) experiment provides distance information for heteronuclear spins. 13C{29Si} REDOR experiments reveal proximities between different organic compounds and the silica phase. The closest contacts between silica and organic compounds appear for different signals in the 13C-chemical shift range of 40 – 60 ppm, the typical range for LCPAs.