Reaction of Ca2+ and phosphate ester

The reaction of calcium ions and organic phosphate ester monomer at varying pHs was examined. Above pH 10, poorly crystallized hydroxyapatite was formed, which had lower crystallinity than that synthesized with inorganic phosphate as a source of P under the same conditions. On the other hand, the results of X-ray diffraction, chemical analysis, infrared absorption analysis and differential thermal analysis suggested that, crystalline organic calcium phosphate ester was formed below pH 10, whilst for the synthesis with inorganic phosphate hydroxyapatite was formed at pH 7.4.