Quantitative kinetic analysis of EDOT emulsion polymerization: linking oxidant controlled reaction rate to PEDOT structure and conductivity

Poly(3,4-ethylenedioxythiophene) (PEDOT) is the most researched conducting polymer, yet the oxidative polymerization of its monomer EDOT in aqueous emulsion remains poorly understood. In particular, the influence of oxidant concentration on polymerization kinetics and the resulting structure–property relationship has not been quantitatively established. Here, a quantitative ¹H NMR (q-NMR) protocol was developed, that enables direct time-resolved measurement of EDOT conversion during emulsion polymerization with an anionic surfactant. By coupling q-NMR with kinetic modelling, the rate-determining step is identified as the oxidation of EDOT by iron chloride. It is demonstrated that the polymerization follows pseudo-first-order kinetics governed by the oxidant concentration. Structural and electronic characterization reveals that slower polymerization at lower oxidant ratios promotes increased chain planarity, less surfactant entrapment and enhanced electrical conductivity in PSS-free PEDOT. This work aims to establish a quantitative link between oxidant-controlled reaction rate, structural organization, and conductivity in PEDOT synthesized in emulsion, leading to an improved understanding and optimization for conductive PEDOT materials.