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 × 103 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 π–π⁎ 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)-1-p-tolyl-1H-pyrrole) is a suitable material for electrochromic devices.