Preparation of zincsodium phosphate glass precursors by coacervation

Condensed phosphates of (50 - x)Na2O-xZnO-50P2O5, 36.7 ≤ x ≤ 46.7 are isolated by separation of coacervates from aqueous colloidal solutions. The relation between the occurrence of coacervation and the presence of complexes in zinc-sodium polyphosphate solutions has been investigated by 31P nuclear...

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Bibliographic Details
Published in:Journal of non-crystalline solids 1995-09, Vol.189 (3), p.277-282
Main Authors: Palavit, G., Montagne, L., Delaval, R.
Format: Article
Language:English
Subjects:
Chemistry
Colloidal gels. Colloidal sols
Colloidal state and disperse state
Exact sciences and technology
General and physical chemistry
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Summary:Condensed phosphates of (50 - x)Na2O-xZnO-50P2O5, 36.7 ≤ x ≤ 46.7 are isolated by separation of coacervates from aqueous colloidal solutions. The relation between the occurrence of coacervation and the presence of complexes in zinc-sodium polyphosphate solutions has been investigated by 31P nuclear magnetic resonance and viscosity measurements. Zinc complexes with (PO3−) ligands occur whatever the concentration, Zn/P ratios, counter-ion nature and pH. The coacervation does not coincide with a definite complex nature, but rather on electrostatic-stability-related criteria of the polyphosphate anions. These electrostatic criteria explain the dependence of the zinc-sodium polyphosphate coacervation on the pH and nature of the counter-ion. A method of preparation of powdered glass precursors from coacervates and their formulations are described.
ISSN:0022-3093
1873-4812
DOI:10.1016/0022-3093(95)00236-7