In Situ Synthesis of Poly(3,4‐Ethylenedioxythiophene) Analog Using Plasma Inside a Bubble

Poly(3,4‐ethylenedioxythiophene) (PEDOT) is one of the most successful conductive polymers. This study proposes a novel in situ synthesis method for water‐dispersible and conductive oligomeric PEDOT analogs (a‐PEDOT) utilizing plasma generated inside a bubble in an EDOT emulsion. Highly oxidative species generated by the plasma initiate polymerization, introducing hydrophilic groups and inducing hole doping. These reactions were found to progress continuously over a 7‐day period due to the presence of long‐lived oxidants such as H 2 O 2 dissolved in the emulsion. The introduction of O 2 into the plasma‐forming gas significantly promoted polymerization and the formation of polaronic oligomeric a‐PEDOT, resulting in enhanced film conductivity. However, under a constant applied voltage, an excessive O 2 supply led to a decrease in conductivity.