Hydrolysis of tetracalcium phosphate in the presence of a poly(alkenoic acid)

摘要

Ca_4(PO_4)_2O (TetCP) reacts withan acidic polyelectrolyte in the absence of a solvent toform a solvent to form a composite composed ofCa_10(PO_4)_6(OH)_2 (hydroxyapatite, or Hap) andthe Ca salt of the polyelectrolyte. Mixtures of anacrylic copolymer and TetCP powders were hot-pressed, and the effects of temperature, pressure, andtime on HAp formation were studied. Reaction startswhen the copolymer is heated to above T_g Initialcarboxyl site neutralization liberates water, continuedTetCP hydrolysis, liberates Ca~2+ ions, which reactwith the copolymer forming its Ca salt. When90percent conversion to HAp was achieved, thecomposite had an average tensile strength of 51 MPa, aVickers hardness of 145 kg/mm~2 and a T_g ~ 250 beg C.