Structure and glass transition of amorphous materials composed of titanium-oxo oligomers chemically modified with benzoylacetone

Abstract

Titanium-n-butoxide was hydrolyzed in the presence of benzoylacetone, and the resulting solution was concentrated and dried at 120 or 140 °C to obtain transparent amorphous materials. High-energy X-ray diffraction measurement was conducted at the SPring-8 facility, and the reduced pair distribution function, G(r) was calculated by Fourier transform of the total structure factor, S(Q). The G(r) value suggested that the materials are composed of TiO₆ octahedra linked by corner- and edge-sharing. Low temperature thermomechanical analysis (TMA) and differential scanning calorimetry (DSC) were conduced on the materials, where a deflection was detected both in the TMA and DSC curves, revealing the glass transition of the materials. Combined with the previous work based on infrared absorption spectroscopy and gel permeation chromatography, the materials are demonstrated to be a new class of glassy materials composed of linked metal-oxygen polyhedra chelated with organic molecules. The materials are innovative due to the high refractive indices that originate in the metal-oxo oligomers and to the shapability given by their thermoplastic properties.