Hydrolysis of doped conducting polymers

Vithyasaahar Sethumadhavan; Kamil Zuber; Christopher Bassell; Peter R Teasdale; Drew Evans

doi:10.1038/s42004-020-00404-y

Hydrolysis of doped conducting polymers

Commun Chem. 2020 Nov 4;3(1):153. doi: 10.1038/s42004-020-00404-y.

Authors

Vithyasaahar Sethumadhavan¹, Kamil Zuber¹, Christopher Bassell¹, Peter R Teasdale², Drew Evans³

Affiliations

¹ Future Industries Institute, University of South Australia, Mawson Lakes, SA, 5095, Australia.
² UniSA STEM, University of South Australia, Mawson Lakes, SA, 5095, Australia.
³ Future Industries Institute, University of South Australia, Mawson Lakes, SA, 5095, Australia. Drew.evans@unisa.edu.au.

Abstract

Conducting polymers display a range of interesting properties, from electrical conduction to tunable optical absorption and mechanical flexibility, to name but a few. Their properties arise from positive charges (carbocations) on their conjugated backbone that are stabilised by counterions doped in the polymer matrix. In this research we report hydrolysis of these carbocations when poly(3,4-ethylenedioxy thiophene) is exposed to 1 mM aqueous salt solutions. Remarkably, two classes of anion interactions are revealed; anions that oxidise PEDOT via a doping process, and those that facilitate the S_N1 hydrolysis of the carbocation to create hydroxylated PEDOT. A pKa of 6.4 for the conjugate acid of the anion approximately marks the transition between chemical oxidation and hydrolysis. PEDOT can be cycled between hydrolysis and oxidation by alternating exposure to different salt solutions. This has ramifications for using doped conducting polymers in aqueous environments (such as sensing, energy storage and biomedical devices).

Grants and funding

FT160100300/Department of Education and Training | Australian Research Council (ARC)