Formation of functional phosphosilicate gels from phytic acid and tetraethyl orthosilicate

Qiu, Dong and Guerry, Paul and Knowles, Jonathan C. and Smith, Mark E. and Newport, Robert J. (2008) Formation of functional phosphosilicate gels from phytic acid and tetraethyl orthosilicate. Journal of Sol-Gel Science and Technology, 48 (3). pp. 378-383. ISSN 0928-0707. (doi: (Access to this publication is currently restricted. You may be able to access a copy if URLs are provided)

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Phosphosilicate gels with high phosphorus content (P mol% > Si mol%) have been prepared using phytic acid as the phosphorus precursor, with tetraethyl orthosilicate (TEOS). It is shown that the structure of phytic acid is maintained in both the sols and those gels dried at a low temperature (i.e. <= 120 degrees C). Solid state Si-29 and P-31 NMR suggest that the gel network is primarily based on tetrahedral silicon and that phosphorus is not chemically incorporated into the silicate network at this point. X-ray diffraction shows the gel to be amorphous at low temperatures. After heat treatment at higher temperatures (i.e. up to 450 degrees C), P-O-Si linkages are formed and the silicon coordination changes from tetrahedral to octahedral. At the same time, the gel crystallizes. Even after this partial calcination,P-31 NMR shows that a large fraction of phytic acid remains in the network. The function of phytic acid as chelating agent is also maintained in the gels dried at 120 degrees C such that its ability to absorb Ca2+ from aqueous solution is preserved.

Item Type: Article
Uncontrolled keywords: Phosphosilicate Sol-gel Si-29 and P-31 NMR Calcium absorbing
Subjects: Q Science
Divisions: Faculties > Sciences > School of Physical Sciences > Functional Materials Group
Depositing User: J.M. Smith
Date Deposited: 12 May 2009 16:02 UTC
Last Modified: 07 Apr 2014 11:35 UTC
Resource URI: (The current URI for this page, for reference purposes)
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