An easily functionalizable oligo(oxyethylene)- and ester-substituted poly(3,4-propylenedioxythiophene) derivative exhibiting alkali metal ion response

Abstract

A new poly(3,4-propylenedioxythiophene) (PProDOT) derivative combining ion complexing oligoether units and a reactive ester group in the side chain obtained by oxidative chemical and electrochemical polymerization of the corresponding ProDOT monomer is described. The P(ProDOT-EO-ester) chemically synthesized after dedoping reveals a strong UV blue shift in THF in the presence of Na⁺ and K⁺, respectively, indicating conformational disordering and a substantially decreased conjugation of the polymer chain induced by ion complexation. Post-polymerization functionalization can be achieved by treatment with hydrazine hydrate leading to partial hydrazinolysis of the ester group. The electrogrowth process of the polymer on ITO is carried out using Bu₄NClO₄ or LiClO₄ as supporting electrolyte, resulting in the formation of conductive thin films. Cyclic voltammetry reveals a slight shift of the redox peaks to lower potentials in the presence of Li⁺.