Apatite-forming ability and mechanical properties of PTMO-modified CaO-SiO₂-TiO₂ hybrids derived from sol-gel processing

Hydrolysis and polycondensation of triethoxysilane end-capped Poly (tetramethylene oxide) (Si-PTMO), tetraethoxysilane (TEOS), tetraisopropyltitanate (TiPT) and calcium nitrate (Ca(NO₃) ₂) gave transparent monolithics of PTMO-modified CaO-SiO ₂-TiO₂ hybrids. The samples with (TiPT)/(TEOS+TiPT) molar ratios from 0 to 0.20 under constant ratio of (Si-PTMO)/(TEOS+TiPT) of 2/3 in weight were prepared. It was found that the incorporation of TiO₂ component into a PTMO-CaO-SiO₂ hybrid results in an increase in the apatite-forming ability in a simulated body fluid: the hybrids with (TiPT)/(TEOS+TiPT) of 0.10 and 0.20 in mol formed an apatite on their surfaces within only 0.5 day. It seemed that, within the range of compositions studied, the TiO₂ content little affects the overall mechanical properties: Young's modulus were 52-55MPa, tensile strength, 7-9MPa, and strain at failure, about 30%. Thus, the organic-inorganic hybrids exhibiting both fairly high apatite-forming ability and high capability for deformation were obtained. These hybrid materials may be useful as new kind of bioactive bone-repairing materials.