Synthesis, characterization and optoelectrochemical properties of poly(1,6-bis(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)hexane) and its copolymer with EDOT

A new polythiophene derivative was synthesized by electrochemical oxidative polymerization of 1,6-bis(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)hexane (TPH). The structure of the monomer was elucidated by 1H, 13C, FTIR and mass analyses. The polymer P(TPH) and its copolymer with 3,4-ethylenedioxythiophene (P(TPH-co-EDOT)) were synthesized via potentiostatic electrochemical polymerization. Characterizations of the resulting polymers were performed by cyclic voltammetry (CV), FTIR, UV–vis spectroscopies and conductivity measurements. Moreover, the spectroelectrochemical and electrochromic properties of the polymer films were investigated. While P(TPH) has only three colors in oxidized and neutral states (blue, green and yellow), its copolymer with EDOT has five different colors (purple, red, light gray, green, and blue). Optical contrast and switching time of the polymer film were improved via copolymerization. It was found that with increasing applied potential the amount of PEDOT in the copolymer composition increases and band gap (Eg) of the copolymer decreases.