Conducting poly(3,4-ethylenedioxythiophene) materials with sustainable carrageenan counter-ions and their thermoelectric properties

Abstract

The preparation and properties of conducting polymers comprising poly(3,4-ethylenedioxythiophene) (PEDOT) and two types of carrageenan – each on their own or combined – as counter-ions are described. The aim of the work is to provide alternative, more sustainable materials that can complement the existing variety of conducting polymers based on the same doped poly(thiophene) derivative. The materials were prepared using chemical oxidation of the 3,4-ethylenedioxythiophene (EDOT) monomer in water. The naturally-occurring polymers kappa- and lambda-carrageenan (bearing one and three sulphate groups per disaccharide monomer unit, respectively) were present during the polymerisation, and are proved to be present in the final composite by infrared and X-ray photoelectron spectroscopies and matrix-assisted laser desorption-ionisation mass spectrometry. The materials produced in this work show good conductivity in thin film form by casting from suspensions (between 1 and 14 S cm⁻¹) and in addition show thermoelectric properties that make them attractive for a range of functionalities.