Synthesis and electrical properties of PEDOT/PSSA conducting polymer complex

Abstract

The first objective of this study was to correlate the operating conditions for the synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) with its chemical characteristics and to incorporate these chemical characteristics with electronic and optical properties of the polymer. And the second objective was to synthesize poly(3,4-ethylenedioxythiophene) with poly(styrenesulfonic acid) (PSSA) as a template in aqueous solution by using potassium persulfate (KPS) and to investigate the chemical characteristics, electronic and optical properties of these polymer. The PEDOT samples were synthesized from aqueous solutions of KPS and 3,4-ethylene dioxythiophene (EDOT). Samples with different chemical characteristics were obtained by varying the initial concentrations of KPS and EDOT in the polymerization solutions. The initial concentration of KPS and EDOT varied from 0.0176 M KPS/0.0352 M EDOT to 0.2816 M KPS/0.0704 M EDOT. The reaction involved the polymerization and doping of PEDOT with electrical conductivity in one step. And the PEDOTs produced from different initial concentrations of KPS and EDOT had different chain and conjugation lengths and different concentrations of chemical defect sites. The electrical conductivity and yield of PEDOT increased as the molar ratio of KPS to EDOT increased until the molar ratio of unity. Then they decreased. Both electronic and optical conductivity was affected by the changes in conjugation length and doping level. The kinetics of chemical polymerization of EDOT with and without PSSA (used as a template) were studied. A calorimeter was used to directly monitor the rate of emulsion polymerization of EDOT in aqueous solution for different concentrations of the initiator, KPS. The reaction rate was found to be governed by the concentration of the reactants in the conventional polymerization without PSSA: $R_p ∝ [KPS]^{0.66} × [EDOT]^{0.27}$. The exponent of EDOT concentration had so low value that the reaction was the approximately...