Surface and related bulk properties of titania nanoparticles recovered from aramid–titania hybrid films: A novel attempt

Abstract

5 and 10wt%-TiO2-containing aramid–titania hybrid films were prepared using sol–gel processing improved by the inclusion of 3-isocyanato-propyltriethoxysilane (ICTOS) to strengthen bonding of the titania species to the polymer backbone and, hence, lessen its agglomeration. The films were thermally degraded by heating at 450°C in a dynamic atmosphere of air. The solid residues were found by thermogravimetry, X-ray diffractometry and electron microscopy to consist dominantly of uniformly agglomerated rod-like anatase-TiO2 nanoparticles, irrespective of the titania content of the film. The recovered titania particle morphology and surface microstructure were examined by field emission scanning and high-resolution transmission electron microscopy, respectively. Whereas, the particle surface chemistry and texture were assessed, respectively, by means of X-ray photoelectron spectroscopy and N2 sorptiometry. The recovered titanias were found, irrespective of the film content of titania, to enjoy not only a high temperature (up to 800°C) stable nanoscopic anatase bulk structure, but also a high-temperature stable surface chemical composition (lattice Ti4+ and O2−, and adsorbed OH/CHx species), (101)-faceted microstructure and highly accessible (145–112m2/g), uniform mesoporous texture with average pore diameter in the narrow range of 3.9–6.3nm. Increasing the calcination temperature up to 1100°C enhances an anatase→rutile transition, the extent of which is larger the higher the titania content of the film.