TiO2 nanorods (diameter of 6–8 nm) with the rutile-type structure have been investigated by Raman spectroscopy under high pressure. Additional bands in the Raman spectrum at ambient pressure are interpreted as resulting from defects that break the Raman selection rules as the simulated vibrational density of states (vDOS) is in good agreement with the experimental spectrum. Under pressure, the rutile structure transforms to the baddeleyite one at P ∼ 16 GPa. After the pressure cycle, the α-PbO2 phase is recovered. The sequence of phases is discussed in terms of thermodynamics and kinetics based on crystallographic relationships. In contrast to other one-dimensional TiO2 nanomaterials that adopt a metastable structure, the nanorods studied in this work show little impact of the morphology on the phase transitions sequence compared to that of the bulk TiO2.

Organic/inorganic hybrid coatings prepared via the sol-gel process have received lot of interests during the early twenty-first century. Devices obtained thanks to this low-temperature route display a large panel of bulk and surface properties that can be modulated according to the target. Moreover, this versatility enables to offer solutions in various domains and industrial applications such as microelectronics, optic, aeronautic, automotive, health. When the aimed application required polymer as substrate, the use of sol-gel process takes its full interest as soft chemistry. This review is dedicated to mechanical properties improvement of a common polymer substrate, e.g., polycarbonate, when a transparent sol-gel coating recovered it. Graphical Abstract