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1 Polish Journal of Chemistry

1 2007

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Preparation and Characterization of Polysiloxane Xerogels Having Covalently Attached Phosphonic Groups

Dąbrowski A., Barczak M., Dudarko O., Zub Y.

Polish Journal of Chemistry

2007

Vol. 81, nr 4

475-483

Porous materials with residual phosphonic –P(O)(OH)2 groups (2.6–3.5 mmolg–1) were synthesized by acidic treatment of nonporous xerogels containing Si(CH2)2P(O)(OC2H5)2 functional groups. Elemental analysis, IR and solid-state NMR data clearly show that the structure of the functional layer of such xerogels is stable against further destruction under boiling concentrated HCl for 24 h. Thermal analysis results testify that the functional layer is stable up to 150C. An increase in the relative quantity of the structure-forming agent (tethraethoxysilane) during the synthesis of initial xerogels results in an increase of a specific surface area of the phosphonic acid-modified xerogels (till 720 m2/g). The 31P CP/MASNMRdata indicate that a part of phosphonic acid groups forms –(HO)(O)P–O–Si linkages during vacuum drying due to phosphonic-silanol groups reaction.