Apatite-Forming Ability and Mechanical Properties of Poly(tetramethylene oxide) (PTMO)-Ta₂O₅ Hybrids

Calcium-free poly(tetramethylene oxide) (PTMO)-Ta₂O₅ hybrids were prepared by a sol-gel method from triethoxysilane-functionalized PTMO (Si-PTMO) and tantalum ethoxide (Ta(OEt)₅) with Si-PTMO/Ta(OEt)₅ mass ratio of 30/70, 40/60 and 50/50 (hybrids PT30Ca0, PT40Ca0 and PT50Ca0, respectively). A calcium-containing PTMO-Ta ₂O₅ hybrid was prepared from Si-PTMO, Ta(OEt)₅ and CaCl₂ with Si-PTMO/Ta(OEt)₅ weight ratio of 40/60 and CaCl₂/Ta(OEt)₅ mole ratio of 0.15 (hybrid PT40Ca15). Crack-free transparent monolithic hybrids were obtained for all the compositions except for PT30Ca0. Hybrids PT40Ca0 and PT50Ca0 formed apatite on their surfaces in a simulated body fluid (SBF) within 14 d. Hybrid PT40Ca0 showed higher mechanical strength and larger strain to failure than human cancellous bone. Its mechanical strength was a little increased by soaking in SBF. Hybrid PT40Ca15 formed apatite on its surface in SBF within 3 d. This hybrid, however, showed a significant decrease in mechanical strength after soaking in SBF. Bioactive flexible materials of calcium-free PTMO-Ta ₂O₅ hybrids are expected to be useful for bone repair.