New TiO_2 precursor for TiO_2:poly(N-vinylcarbazole) (PVK) thin film: Synthesis and reactivity to hydrolysis of titanium tetrakis (9H-carbazole-9-yl-ethyl-oxy)

摘要

The chemical reactivity of the ligand initially coordinated on the TiO_2 precursor plays a decisive role in the morphology of TiO_2:po1y(N-vinylcarbazole)(PVK) thin film elaborated by in situ generation of the inorganic phase in the polymer matrix. The final aim of this study is to prepare a new nanocomposite TiO_2:poly(N-vinylcarbazole) (PVK) thin film from hydrolysis-condensation of titanium alkoxide in poly_mer thin film. In this context, we synthesized a new TiO_2 precursor, the tetrakis (9H-carbazole-9-yl_ethyl-oxy) [Ti(OeCarb)_4], bearing ligands close to the repetitive unit structure of the PVK to improve the interaction between both materials. In this study, the synthesis and reactivity to hydrolysis of Ti(Oe_Carb)_4 is presented. Ti(OeCarb)_4 was elaborated from alcoholysis reaction between titanium isopropoxide [Ti(~1OPr)_4] and 9H-carbazole-9-ethanol (ECOH) and identified by ~1H and ~13C NMR spectroscopy. The reac_tivity to hydrolysis-oxolation of Ti(OeCarb)_4 was evaluated first in aqueous media by in situ ~1H NMR spectroscopy analysis. Moreover, reactivity of Ti(OeCarb)_4 to surrounding humidity was evaluated in thin film by X-ray photoelectron spectroscopy (XPS). Results show that steric hindrance of 9H-carbazole-9-vl_ethyl-oxide ligands do not influence the hydrolysis-condensation process in aqueous media in our exper_imental conditions when compared to (Ti(~1OPr)_4) but decrease the reactivity when the precursor is simply exposed to air humidity.