Electrochemical Gating of Doped Polymeric Semiconductors with Hydrogen Bonding Side Chains

Abstract

This thesis aims to explore the potential impact of mixed ionic-electronic conductivity resulting from addition of hydrogen-bonding side chains to polymeric semiconductors. This unique functionality enables the direct use of such materials in bioelectronics applications, where ionic-electronic interfaces in hydrated environments are highly desired.

Aim 1 discusses a preliminary work quantifying the mixed conductivity of a carboxylated polythiophene that initially functioned as a polymeric binder for magnetite-based anodes. Aim 2 expands on Aim 1 to quantify the impact of alkyl spacer length on mixed conduction in aqueous systems. Electrochemical studies on these poly[3-(carboxyalkyl)thiophene]s (alkyl spacer length = 3 – 5) indicate that side chain length does not play a significant role in dictating the doping kinetics in aqueous media. Aim 3 moves beyond the simple model polythiophene backbone and examines how ester and carboxylic acid-based side chains impact the aqueous electroactivity of a high mobility donor-acceptor backbone. Compared to their polythiophene counterparts, the functionalized donor-acceptor polymers demonstrated little electroactivity in aqueous media. These contrary results indicate that addition of hydrogen-bonding side chains may play a role in inducing aqueous electroactivity in select polymers, but that additional explorations in chemical structure and side chain engineering are needed to qualitatively predict whether polymers can be made aqueous electroactive.