Electrochemical Copolymerization Of3,4-ethylenedioxythiophene And Indole Derivatives And Their Electrochromic Properties

The investigation of conducting polymers has focused on the electrosynthesis of conducting polymers and their electrochromic properties. Copolymerization can overcome the limitation of the type of new monomers to prepare new conducting copolymer. Poly(3,4-ethylenedioxythiophene) is the most widely applied one among a large number of conducting polymers. And polyindole family is an important material due to its good electrochromic performance. In this paper, we using the electrochemical polymerization synthesis method to realize the copolymerization of3,4-ethylenedioxythiophene (EDOT) and5-formyindole (5FIn), indole-6-carboxylic (I6CA), respectively. Characterizations and electrochromic properties of corresponding copolymer were discussed.1. Copolymer based on5-formyindole (5FIn) and3,4-ethylenedioxythiophene (EDOT) was electrochemically synthesized in ACN/TBATFB solution. The impact of applied polymerization potential and concentration ratios of3,4-ethylenedioxythiophene and5-cyanoindole on the electrochemical polymerization synthesis of copolymer were investigated.0.08mol L-1EDOT vs0.02mol L-15FIn was proved to be the best concentration ratio for the electrochemical copolymerization. At the same time, the copolymer possess good redox activity, electrochemical properties and good thermal. The copolymer is also a good green-light emitter and its fluorescence quantum yield is0.85. Electrochromic properties were investigated meanwhile, the copolymer could change from brick red (reduced) to blue (oxidized). This copolymer showed good optical contrast (40.2%at460nm), coloration efficiency (183cm2/C). The switching time was found to be0.75s from the reduced to the oxidized state and0.90s from the oxidized to the reduced state. 2. Copolymer based on indole-6-carboxylic (I6CA) and3,4-ethylenedioxythiophene (EDOT) was electrochemically synthesized in ACN/TBATFB solution. The influence of applied polymerization potential and concentration ratios of3,4-ethylenedioxythiophene and indole-6-carboxylic on the electrochemical polymerization synthesis of copolymer were investigated. By comparative study, we found that1.45V vs. SCE was proved to be the best potential for the electrochemical copolymerization of EDOT and I6CA. At the same time, the copolymer possess good redox activity, electrochemical properties and good thermal. We tested the conductivity of copolymers is24.60S cm-1. In addition, the copolymer film exhibits electrochromism and the electrochromic properties were investigated. The copolymer could change from orange (reduced) to blue (oxidized) and achieved a high coloration efficiency of142cm2/C at465nm and158cm2/C at800nm.