Apatite-Forming Ability and Mechanical Behavior of PTMO-Modified CaO-TiO2 Hybrids Prepared by Sol-Gel Processing

Triethoxysilane end-capped poly (tetramethylene oxide) (Si-PTMO)-modified CaO-TiO2 hybrids were prepared by hydrolysis and polycondensation of Si-PTMO, tetraisopropyltitanate (TiPT) and calcium nitrate. Under constant weight ratio of (Si-PTMO)/(TiPT) = 2/3, the molar ratio of (Ca(NO3)2)/TiPT) was varied from 0 to 0.15. The apatite-forming ability was evaluated in a simulated body fluid (SBF), and the mechanical properties including Young's modulus, strength and strain at failure were measured in air by three-point bending. The apatite-forming ability in SBF increased significantly with increasing CaO content, although the bending strength and Young's modulus decreased. The hybrid samples with (Ca(NO3)2) /(TiPT) = 0.10 and 0.15 in mol, respectively, formed apatite on their surface within only one day. The failure strains were found to be in the range of about 13 to 25%. Thus, hybrids showing both high apatite-forming ability and high capability for deformation were successfully synthesised. These hybrids may be useful as novel bioactive bone-repair materials. 11 refs.