A soluble conducting polymer of 2,5-di(thiophen-2-yl)-1-p-tolyl-1H-pyrrole and its electrochromic device

A monomer 2,5-di(thiophen-2-yl)-1-p-tolyl-1H-pyrrole was synthesized via reaction of 1,4-di(2-thienyl)-1,4-butanedione and p-toluidine in the presence of catalytical amount of p-toluenesulfonic acid. Chemical polymerization of the monomer yielded a soluble polymer. The average molecular weight was determined by gel permeation chromatography as number average molecular weight (Mn) 2.5 x 10(3) g/mol. The monomer was also electrochemically polymerized in the presence of LiClO4, NaClO4 (1:1) as the supporting electrolyte in acetonitrile. Cyclic Voltammetry, Fourier Transform Infra Red, Nuclear Magnetic Resonance, Scanning Electron Microscopy and Ultraviolet-Visible Spectroscopy were employed for the characterization of the polymer. Spectroelectrochemistry analysis of homopolymer revealed an electronic transition at 428 nm which corresponds to pi-pi* transition. Switching ability of the homopolymer was evaluated by kinetic studies upon measuring the percent transmittance (%T) at the maximum contrast point, indicating that poly(2,5-di(thiophen-2-yl)-l-p-tolyl-IH-pyrrole) is a suitable material for electrochromic devices. (c) 2006 Elsevier B.V. All rights reserved.