Styrene-Maleic Anhydride Copolymers for High-Performance Triarylamine-Containing Electrochromic Materials

Abstract

A facile approach was employed to produce thermosets of styrene-maleic anhydride copolymers (SMA) containing three kinds of triarylamine moieties to elucidate electrochromic (EC) behaviors comprehensively, and an additional ionization modification was also applied to explore the effect on counterion diffusion kinetics during the electrochemical process. The commercially available SMA was chosen as the starting material for coupling with three triarylamine-based diamine monomers, 4,4′-diamino-4″-methoxytriphenylamine (3Ph), N,N′bis(4-aminophenyl)-N,N′-di(4-methoxylphenyl)-1,4-phenylenediamine (5Ph), and 4,4′-bis[4-aminophenyl(4-methoxyphenyl)amino)]-4″-methoxytriphenylamine (7Ph), resulting in colorless and transparent thermoset polymer films with different interchain distances. Furthermore, the precursors of these polyamic acids could be reacted with triethylamine (Et 3 N) to form the related triethylammonium-containing PAA complexes, which could facilitate the migration of counterion during redox procedures. After evaluating the electrochemical and EC behaviors, we demonstrate that the merge of enlarging interchain distance and ionization modifications in the triarylamine-coupling SMA copolymer matrixes leads to synergistic effects in the diffusion dynamics of the electrolyte counterion and could effectively enhance higher diffusion rates (D) of the counterion in the polymer matrix with more than 2,400 times larger (iS5Ph: 96.73 cm 2 s −1 10 −18 ) than the triphenylamine-based linear type polyimide, L3Ph (0.04 cm 2 s −1 10 −18 ), and the prepared electrochromic device (ECD) properties revealed faster coloration response speed (υ c ) 43.7% s −1 and outstanding coloration efficiency (η CE ) up to 540 cm 2 /C.