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Porous hybrid inorganic-organic phosphosilicate materials by non-hydrolytic sol-gel polycondensation reactions

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Year of publication 2013
Type Conference abstract
MU Faculty or unit

Central European Institute of Technology

Description Non-hydrolytic condensation reactions became a powerful substitute for aqueous techniques in the area of sol-gel synthesis of multimetallic oxides and inorganic-organic hybrid materials in the form of xerogels, nanoparticles, and thin films. We developed a non-hydrolytic sol-gel route based on acetic acid ester elimination providing phosphosilicate hybrid inorganic-organic materials. The polycondensation reactions between Si(OAc)4 and OP(OSiMe3)3 led to microporous phosphosilicate xerogels with surface areas up to 568 m2 g-1. The consecutive substitution of Si and P precursors by acetoxysilanes 1RxSi(OC(O)CH3)4-x (1R = Me, Ph; x = 1-2) and trimethylsilylesters of phosphonic acid 2RP(O)(OSiMe3)2 (2R = c-Hex, Ph) caused the decrease of surface areas and increase of average pore sizes because of the lower cross-linking ability of the substituted precursors. We avoided a significant decrease of surface areas of hybrid xerogels by changing starting precursors to acetoxysilanes and phosphonic acid esters with bridging alkyl or aryl groups (AcO)3Si-(CH2)x-Si(OAc)3 (x = 1-3, 6), (Me3SiO)2P(O)-3R-P(O)(OSiMe3)2 (3R = C2H4, C6H4). Our aim was to study the versatility of these reactions and tune the properties of resulting xerogels, such as surface area, pore size distribution, chemical and thermal stability. The prepared xerogels were characterized by solid-state 13C, 29Si, 31P NMR, IR spectroscopy, surface area analysis, TGA, and XRD.
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