« Previous AbstractAir quality and its possible impacts on the terrestrial ecosystems of the North American Great Plains: an overview    Next AbstractField attraction of the stink bug Euschistus conspersus (Hemiptera: Pentatomidae) to synthetic pheromone-baited host plants »

Gels

Title:		A Non-Hydrolytic Sol-Gel Route to Organic-Inorganic Hybrid Polymers: Linearly Expanded Silica and Silsesquioxanes
Author(s):		Krupinski K; Wagler J; Brendler E; Kroke E;
Address:		"Institute of Inorganic Chemistry, Department of Chemistry and Physics, Technische Universitat Bergakademie Freiberg (TUBAF), Leipziger Strasse 29, 09596 Freiberg, Saxony, Germany. Center of Efficient High Temperature Processes and Material Conversion (ZeHS), Technische Universitat Bergakademie Freiberg (TUBAF), Winklerstr. 5, 09599 Freiberg, Saxony, Germany. Institute of Analytical Chemistry, Department of Chemistry and Physics, Technische Universitat Bergakademie Freiberg (TUBAF), Leipziger Strasse 29, 09596 Freiberg, Saxony, Germany"
Journal Title:		Gels
Year:		2023
Volume:		20230402
Issue:		4
Page Number:		-
DOI:		10.3390/gels9040291
ISSN/ISBN:		2310-2861 (Electronic) 2310-2861 (Linking)
Abstract:		"Condensation reactions of chlorosilanes (SiCl(4) and CH(3)SiCl(3)) and bis(trimethylsilyl)ethers of rigid, quasi-linear diols (CH(3))(3)SiO-AR-OSi(CH(3))(3) (AR = 4,4'-biphenylene (1) and 2,6-naphthylene (2)), with release of (CH(3))(3)SiCl as a volatile byproduct, afforded novel hybrid materials that feature Si-O-C bridges. The precursors 1 and 2 were characterized using FTIR and multinuclear ((1)H, (13)C, (29)Si) NMR spectroscopy as well as single-crystal X-ray diffraction analysis in case of 2. Pyridine-catalyzed and non-catalyzed transformations were performed in THF at room temperature and at 60 degrees C. In most cases, soluble oligomers were obtained. The progress of these transsilylations was monitored in solution with (29)Si NMR spectroscopy. Pyridine-catalyzed reactions with CH(3)SiCl(3) proceeded until complete substitution of all chlorine atoms; however, no gelation or precipitation was found. In case of pyridine-catalyzed reactions of 1 and 2 with SiCl(4), a Sol-Gel transition was observed. Ageing and syneresis yielded xerogels 1A and 2A, which exhibited large linear shrinkage of 57-59% and consequently low BET surface area of 10 m(2)?nag(-1). The xerogels were analyzed using powder-XRD, solid state (29)Si NMR and FTIR spectroscopy, SEM/EDX, elemental analysis, and thermal gravimetric analysis. The SiCl(4)-derived amorphous xerogels consist of hydrolytically sensitive three-dimensional networks of SiO(4)-units linked by the arylene groups. The non-hydrolytic approach to hybrid materials may be applied to other silylated precursors, if the reactivity of the corresponding chlorine compound is sufficient"
Keywords:		29Si solid state NMR arylene bridged chlorosilanes inorganic/organic networks non-aqueous gels pyridine;
Notes:		"PubMed-not-MEDLINEKrupinski, Katrin Wagler, Jorg Brendler, Erica Kroke, Edwin eng Switzerland 2023/04/27 Gels. 2023 Apr 2; 9(4):291. doi: 10.3390/gels9040291"