Electrosyntheses and characterizations of novel electrochromic copolymers based on pyrene and 3,4-ethylenedioxythiophene

The copolymers based on pyrene and 3,4-ethylenedioxythiophene (EDOT) are electrochemically synthesized in acetonitrile (ACN) containing tetrabutylammonium perchlorate (TBAP) via the direct oxidation of pyrene/EDOT mixtures. FT-IR and 1H NMR characterizations confirm that the obtained polymers contain both pyrene and EDOT units. Elemental analyses results show that the ratio of pyrene/EDOT units in polymers decreases as the feed ratio of pyrene/EDOT decreases in ACN. The effects of pyrene/EDOT feed ratio and polymerization potential on the electrochemical properties of the obtained copolymers are studied by cyclic voltammetry (CV). Compared with polypyrene, the copolymers perform reversible redox process, and their UV–vis absorption peaks exhibit obvious red-shift. It is interesting that the obtained copolymer films present a property of tunable electrochromism, smooth morphology and good thermal stability.