Study on the preparation and characterization of biodegradable polylactide/SiO2-TiO2 hybrids

In this study, the silicic acid produced from sodium metasilicate hydrate and titanium tetraisopropylate were chosen as the ceramic precursors for the modification of biodegradable polylactide (PLA) through an in situ sol-gel process and the melt blending method. In addition, acrylic acid grafted polylactide (PLA-g-AA) was studied as an alternative to PLA. Hybrids were characterized by Fourier transform infrared spectroscopy, Si-29 solid-state nuclear magnetic resonance (NMR), thermogravimetry analysis (TGA), scanning electron microscope (SEM), and Instron mechanical tester. The result was that properties of the PLA-g-AA/SiO2-TiO2 hybrid were superior to those of the PLA/SiO2-TiO2 hybrid. This was because the carboxylic acid groups of acrylic acid acted as coordination sites for the silica-titania phase to allow the formation of stronger chemical bonds. The Si-29 solid-state NMR showed that Si atoms coordinated around SiO4 units were predominantly Q(3) and Q(4). The 10 wt.% SiO2-TiO2 content gave the maximum values of tensile strength and glass transition temperature in PLA/SiO2-TiO2 and PLA-g-AA/SiO2-TiO2 both because excess SiO2-TiO2 particles caused separation between the organic and inorganic phases.