In-situ preparation of poly(propylene fumarate)--hydroxyapatite composite.

In-situ precipitation of hydroxyapatite (HAp) in the presence of poly(propylene fumarate) (PPF) is investigated. Amorphous calcium phosphate (ACP) precipitates in the presence of the polymer and remains in the amorphous form for a relatively long time, e.g. even after 24 h of coexistence with the mother solution. Our observations suggest that PPF interacts with the surface of the ACP particles and prevents them from transformation to crystalline hydroxyapatite. The PPF polymer seems to be more efficient in hindering the ACP to HAp transformation at higher pH conditions. From spectroscopic observations we hypothesize that the C=O bond of the PPF molecules interact with the calcium ion of the ACP particles. In case of low molecular weight PPF this interaction may lead to the incorporation of the polymer within the growing ACP particles.