Composites of poly(L-lactide-trimethylene carbonate-glycolide) and surface modified SBA-15 as bone repair material

This work aims to develop novel composites from a poly(L-lactide-co-trimethylene carbonate-co-glycolide) (PLTG) terpolymer and mesoporous silica (SBA-15) nanofillers surface modified by post-synthetic functionalization. SBA-15 first reacts with a silane coupling agent, -aminopropyl-trimethoxysilane to introduce ammonium group. PLLA chains were then grafted on the surface of SBA-15 through ammonium initiated ring-opening polymerization of L-lactide. Composites were prepared via solution mixing of PLTG terpolymer and surface modified SBA-15. The structures and properties of pure SBA-15, -aminopropyl-trimethoxysilane modified SBA-15 (H2N-SBA-15), PLLA modified SBA-15 (PLLA-NH-SBA-15), and PLTG/PLLA-NH-SBA-15 composites were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, N-2 adsorption-desorption, differential scanning calorimetry, contact angle measurement, and mechanical testing. The results demonstrated that PLLA chains were successfully grafted onto the surface of SBA-15 with grafting amounts up to 16wt.%. The PLTG/PLLA-NH-SBA-15 composites exhibit good mechanical properties. The tensile strength, Young's modulus, and elongation at break of the composite containing 5wt.% of PLLA-NH-SBA-15 were 39.9MPa, 1.3GPa, and 273.6%, respectively, which were all higher than those of neat PLTG or of the composite containing 5wt.% of pure SBA-15. Cytocompatibility tests showed that the composites present very low cytotoxicity.