Disubstitued thiophene intermediate and monomer were synthesized by the nucleophilic substitution and transetherification reactions. Poly(3,4-dioctyloxythiophene), a soluble conjugated polymer, was synthesized by electrochemical oxidation polymerization. Characterizations of the intermediate, monomer and polymer were performed by 1H-NMR spectroscopy, fourier transform infrared spectroscopy, and gel permeation chromatography. The process of the electrochemical polymerization, electrochemical redox behaviors and electrochromis of the polymer were investigated by the cyclic voltammetry, potentiostatic method and spectroelectrochemical measurement. The polymer film showed stable redox properties, and its redox potentials were between 580mV and 960mV. It was found to exhibit electrochromic behaviors, and switched electrochemically between clear violet reduced and light blue oxidized states. The triplet peaks were observed between 450nm and 650nm in the UV-vis spectra of this polymer, and the maximum contrast transmittance at 600nm was 18.1%.
