New hybrid inorganic-organic complexes based on poly(3-butylthiophene) and titanium tetrachloride: Synthesis, structure and conductivity

This report describes the preparation of two new hybrid inorganic-organic polymer materials to use as electro-active layers in micro-electronic devices. By reacting poly(3-butylthiophene) (PBT) with titanium tetrachloride in a nitrogen atmosphere the hybrid inorganic-organic [(Bu- Th)2TiCl2]n (A) complex (Bu-Th = 3-butylthiophene) was prepared. {[(Bu-Th)2Ti(OH)2(H2O)2]·1.5(H2O)}n (B) was obtained by exposing A to the air. The materials' morphology was examined by scanning electron microscopy (SEM). FT-IR studies provided information about: (a) the structural characteristics of the products; (b) the degree of polymerization; (c) the interactions occurring between the aromatic rings of PBT macromolecular ligand and the titanium metal centers; (d) the effects of the hydration process on coordination geometry of Ti complexes and on the three-dimensional structure of the resulting hybrid inorganic-organic polymer. The thermal behaviour of materials was investigated by thermogravimetry (TGA) and differential scanning calorimetry (DSC). The electrical properties of pristine PBT, A and B materials were studied by broadband dielectric spectroscopy (BDS) in the 40 Hz to 10MHz range, and in the range of temperatures from 173K to about 423 K. The conductivity mechanism was interpreted in terms of charge carrier hoppings between different sites followed by polymer network reorganizations both in bulk grains, and inter-grain interfaces.