Thiophene Ended ϵ‐Caprolactone Conducting Copolymers and their Electrochromic Properties

Abstract

ϵ‐Caprolactone was polymerized by ring‐opening polymerization (ROP), using thiophene methanol as the initiator and stannous octoate as the catalyst to yield poly(ϵ‐caprolactone) with a thiophene end group. Homopolymerization of thiophene functionalized poly (ϵ‐caprolactone) (PCL) was achieved by a constant current electrolysis method. Copolymerizations of PCL with thiophene and pyrrole were achieved in acetonitrile (ACN)‐tetrabutylammonium tetrafluoroborate (TBAFB) solvent‐electrolyte couple via constant potential electrolysis. Characterization of the samples were performed by nuclear magnetic resonance spectroscopy (NMR), cyclic voltammetry (CV), fourier transform infrared spectroscopy (FT‐IR) and scanning electron microscopy (SEM). Electrical conductivities were measured by the four‐probe technique. Spectroelectrochemical behavior of PCL/PTh film, which was deposited on ITO‐glass, was investigated by UV‐Vis Spectrophotometer. Furthermore, it is found to be an anodically coloring copolymer that electrochemically switches between gray‐blue oxidized state and pale red reduced state, exhibiting electrochromic behavior.