Irene Pitsch

Inorganic-organic polymers derived from functional silicic acid derivatives by additive reaction

Abstract Inorganic-organic polymers were synthesized by additive reaction of vinyl-, allyl-, and H-silylated double four-ring (D4R) silicic acids and polymeric silicic acids. The structure and properties of the hybrid polymers were investigated by means of 29Si NMR spectroscopy, thermoanalysis and BET nitrogen adsorption measurements. Using the defined vinylsilylated D4R silicicacid [(CH2CH)(CH3)2Si]8Si8O20 and the corresponding H-silylated compound [(CH3)2HSi]8Si8O20 as precursors, the additive reaction results in a microporous polymer with a ordered Si8O20 substructure. The structural units are connected by six-membered bridges. Shorter (four-membered) or longer (seven-membered) bridges between D4R cages lead to non-porous polymeric materials. The connection of water-glass-derived silicic acid units by six-membered bridges similarly leads to porous polymers with specific surface areas of 500 m2/g. For the preparation of the porous hybrid polymers a new, simple two-step reaction route is described.

Über die Reaktion des käfigartigen Kieselsäurederivats [(CH3)2HSi]8Si8O20 mit ungesättigten organischen Verbindungen

29Si-, 1H- und 13C-NMR-Untersuchungen zeigen, das das Doppelvierring-kieselsaurederivat [(CH3)2HSi]8Si8O20 mit seinen acht HSiGruppen pro Molekul Additionsreaktionen mit den einfach ungesattigten Verbindungen Vinylcyclohexen, Allylglycidylether, Methacrylsauremethylester, Octadecen-1 und Styren eingeht. Die Addition erfolgt uberwiegend entgegen der Markovnikov-Regel. Als Reaktionsprodukte werden meist olartige, in organischen Losungsmitteln losliche Verbindungen der Formeln [C6H9(CH2)2Si(CH3)2]8Si8O20, [CH3OOCCH(CH3)CH2Si(CH3)2]8Si8O20, CH3(CH2)17Si([CH3)2]8Si8O20 und [C6H5(CH2)2Si(CH3)2]8Si8O20 bzw. [C6H5CH(CH3)Si(CH3)2]8Si8O20 erhalten, die durch die chemischen Verschiebungen der 29Si-, 1H- und 13C-NMR-Signale charakterisiert werden. Reaction of the Cage-like Silicic Acid Derivative [(CH3)2HSi]8Si8O20 with Unsaturated Organic Compounds By 29Si, 1H, and 13C NMR investigations were shown that the eight HSigroups of the double four-ring silicic acid derivative [(CH3)2HSi]8Si8O20 react with the following unsaturated compounds: vinylcyclohexene, allyl glycidyl ether, methyl methacrylate, octadecene-1, and styrene. The resulting oily products are soluble in organic solvents. The compounds were characterized by the chemical shifts of the 29Si, 1H, and 13C NMR signals. Their formulae are [C6H9(CH2)2Si(CH3)2]8Si8O20, [CH3OOCCH(CH3)CH2Si(CH3)2]8Si8O20, [CH3(CH2)17Si(CH3)2]8Si8O20 and [C6H5(CH2)2Si(CH3)2]8Si8O20, and [C6H5CH(CH3)Si(CH3)2]8 Si8O20, respectively. Mainly the addition reactions do not follow the Markovnikov rule.

Charakterisierung von Organokieselsäurepolymeren durch thermoanalytische Untersuchungen

Four organosilicate polymers synthesized by addition of vinyl- and H-substituted double four-ring silicic acid derivatives were characterized using DSC and simultaneous TG-DTA measurements. Thermooxidative decomposition proceeds in several steps: Oxidation of (Si−H) groups, oxidation of (Si−CH2−CH2−Si) bridges, and oxidation of (Si−CH3) groups, with formation of new (Si−O−Si) bonds.29Si-NMR-spectroscopic measurements confirm this interpretation. Thermoanlytical methods of investigation proved useful to characterize these organosilicate polymers.ZusammenfassungDurch Addition von Vinyl- und H-substituierten Doppelvierringkieselsäurederivaten hergestellte Organokieselsäurepolymere werden thermonalytisch mit TG-, DTA-and DSC-Messungen charakterisiert. Der thermooxidative Abbau der vier untersuchten Polymere erfolgt in mehreren Schritten: Oxidation der (Si−H)-Gruppen, Oxidation der Ethylenbrücken (Si−CH2−CH2−Si) und Oxidation der (Si−CH3)-Gruppen, jeweils unter Bildung von neuen (Si−O−Si)-Bindungen.29Si-NMR-spektroskopische Ergebnisse stützen die Deutung des Reaktionsablaufsablaufes. Thermoanalytische Untersuchungsmethoden können erfolgreich zur Charakterisierung von Organokieselsäurepolymeren eingesetzt werden.

Solid state 29Si NMR investigation of inorganic-organic polymers with defined silicic acid units

By thermal analysis and 29Si NMR spectroscopy the thermal behaviour and structural changes of two different types of inorganic-organic polymers with defined double four-ring silicic acid units (Si8O20) were characterized. Polymer 1, prepared from the organic silicic acid precursors [(CH3)2HSi]8Si8O20 (Q8M8H) and [CH2=CH(CH3)2Si]8Si8O20 (Q8M8V), preserves the double four-ring structure up to 350°C Higher temperatures lead to structural reorganizations of the SiO4 tetrahedra forming at 900°C a structure similiar to amorphous silica. Polymer 2, synthesized by condensation reaction of the new organic silicic acid precursor [CH3O)3Si(CH2)3OC(O)CH(CH3)CH2Si(CH3)2]8Si8O20, shows with 37% uncondensed SiOH groups a remarkable high content of silanol groups caused by sterical hindrances.