Synthesis and electrochromic properties of novel poly(urethane–azomethine)s containing triphenylamine units

A family of novel electroactive triphenylamine (TPA)-containing aromatic poly(urethane–azomethine)s were prepared from the 2,4-toluene diisocyanate (TDI) and TPA-contained monomers which were synthesized from different diamines and p-hydroxybenzaldehyde. The chemical structures of the polymers have been determined by IR and 1 H NMR. All the polymers which are amorphous, soluble in a variety of organic solvents could be casted into transparent, tough, and flexible films. The thermal properties have been investigated by Thermo Gravimetric Analyzer (TGA) indicating enhanced thermal stabilities compared with the conventional polyurethanes due to the introduction of aromatic TPA groups. These polymers also exhibit excellent acidochromic characteristics with a color change from pale yellow to deep yellow and reversibly electrochromic properties with a color change from yellow to red. The polymers also display photoelectrical response which can act as photoelectrical conversion materials.