Solvent effects on the synthesis, characterization and electrochromic properties of acetic acid modified polyterthiophene

- The derivative of terthiophene oligomer TTAA is electropolymerized in three different systems.
- The effects of three solvents on electrochemical and electrochromic properties of PTTAA are investigated systematically.
- PTTAA as-formerd in BFEE has the best electrochromic performances with coloration efficiency of 391 cm2C−1.

The derivative of terthiophene oligomer 2-(2,5-di(thiophen-2-yl)thiophen-3-yl)acetic acid (TTAA) was synthesized, and its electropolymerization was researched comparatively by using three systems (CH3CN-Bu4NPF6, CH2Cl2-Bu4NPF6, and BFEE). The effects of solvent on the electrochemical, morphology, redox stability, spectroelectrochemical properties and electrochromic performance of the achieved poly(2-(2,5-di(thiophen-2-yl)thiophen-3-yl)acetic acid) (PTTAA) films were studied in detail. PTTAA could be electrosynthesized in all the three systems facilely and displayed wonderful electroactivity and prominent redox stability in a wide potential window. The PTTAA films obtained in CH3CN-Bu4NPF6 and CH2Cl2-Bu4NPF6 had similar electrochemistry property except morphology. PTTAA formed in BFEE had lower oxidation potential (0.4 V) and better cycling stability. Also, it showed moderate response time (1.2 s) and excellent coloration efficiency (391 cm2C−1), enhanced its possible application as electrochromic material. So compared with common solvents CH3CN and CH2Cl2, TTAA could electrochemical polymerization at a lower potential and got higher quality polymer films in the strong Lewis acid BFEE. And this also made PTTAA as-formed in BFEE had better redox stability and electrochromic perfromance.

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