Nanostructural Evolution of Titania-Based Materials Using Modified Titanium Precursors

Titanium ethoxide [Ti(OEt)(4)] was modified with aminobenzoic acid (AB) or aminosalicylic acid (AS) in order to control the hydrolysis and condensation rates, and to allow the preparation of organic-inorganic hybrid materials. A suite of complementary techniques, including Fourier transform infrared spectroscopy, NMR, SEM, thermogravimetric analysis, and X-ray diffraction, were used to elucidate the effects of incorporating an organic functional group into the precursor chemistry and its subsequent affect on the structure and morphology of the resultant hybrid material. The annealing behavior of the resulting hybrid titanium base materials was also investigated. Our studies show that both amino acid organic ligands, AB and AS, chemically bounded to the titanium complex, effect the precursor reactivity, specifically the hydrolysis and polycondensation reactions, which control the evolution and formation of the nanohybrid-based titania material. Following sol-gel processing, the nanohybrid materials are amorphous, due to the incorporation of the organic component. The phase transition (amorphous-anatase-rutile) observed during annealing from 25 degrees to 800 degrees C show subtle differences in the crystallization behavior, which are associated with the nature of the organic ligand.