New polysilsesquioxane materials of ladder-like structure

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• 作者：M. H ; ke ; B. H ; ke ; A. Kowalewska ; W. Jastrzę ; bski
• 关键词：Siloxanes materials ; Mesoporous silica ; IR spectroscopy ; Sol– ; gel method
• 刊名：Journal of Molecular Structure
• 出版年：2009
• 出版时间：30 April 2009
• 年：2009
• 卷：924-926
• 期：Complete
• 页码：254-263
• 全文大小：1093 K

文摘

Alkoxy derivatives of linear oligomethylsiloxanes were applied as substrates for preparation of novel type, ladder-like polymeric silsesquioxane–siloxane materials. A systematic study of the effect of diverging the structure of a polysiloxane chain (distribution of alkoxysilyl groups along the polymer chain) on the properties of silsesquioxane materials obtained by condensation of ethoxy groups, has been undertaken. A series of polysiloxane materials cross-linked with –SiOSi– bonds, forming ladder-like linkages between main siloxane chains was prepared. There were used siloxanes of a regular structure with formula [M(D₂D^OR)₁₀D₂M] and [M(D₂D^OR₂)₁₀D₂M] ] as well as siloxane oligomers of random distribution of MeSi-OR (D^OR) units along the main siloxane chain [MD_(1−x)D^OR_xM (x = 0.3, 0.5, 1.0)]. Alkoxy-functionalized oligosiloxane precursors were cross-linked under hydrolytic condensation conditions catalyzed by HCl/NH₄OH system or nucleophilic catalysts (TBAF and TBAH). The relationship between the structure of siloxane chain (the amount of Si-OR units and their distribution along the polymer backbone) and the properties of obtained preceramic materials was studied with FTIR (as a main method) and NMR, XRD, DTA. The surface area and pores distributions of the studied samples were measured using nitrogen adsorption methods (BET).