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 10 MHz range, and in the range of temperatures from 173 K 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.