Ceramics-Silikáty 51, (1) 1 - 8 (2007) |
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TEXTURAL AND STRUCTURAL PROPERTIES OF BIOACTIVE GLASSES IN THE SYSTEM CaO–SiO₂
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Coleman Nichola J. 1, Bellantone Maria 2, Nicholson John W. 1,
Mendham Andrew P. 1
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1 School of Science, University of Greenwich, Chatham Maritime, Kent, ME4 4TB, UK
2 Nature Materials, The Macmillan Building, 4 Crinan Street, London, N1 9XY, UK
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Keywords: Sol-gel, Bioactive, Mesoporous, Glass
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Gel-derived CaO-SiO₂ binary glasses of CaO mole fractions 0.2, 0.3 and 0.4 have been prepared and characterised. Pore
diameter, specific pore volume, skeletal density and porosity were found to increase with increasing CaO-content, whereas a
concomitant decrease in specific surface area was observed. ²⁹Si NMR indicated that the 0.2 CaO mole fraction glass consisted
of highly polymerized Q⁴ and Q³ silicate species, with some Q² units. With increasing CaO mole fraction, these silicate
species became progressively depolymerised such that isolated SiO₄ tetrahedra were detected within the 0.4 CaO glass matrix.
Unusually, the glasses retained a proportion of Q⁴ and Q³ species as the CaO mole fraction was increased. All glass formulations
exhibited in vitro bioactivity. The rate of hydroxyapatite precipitation followed the order 0.2 CaO > 0.4 CaO > > 0.3
CaO, an effect that is attributed to differences in the rate of dissolution of calcium from these glasses. This, in turn, appears
to be dependent upon the proportion of Ca²⁺ participating in the formation of the glassy network. |
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