Two diamine monomers with methyl (CH3TPA) and methoxy (OCH3TPA) group substituents in the para position of the triphenylamine (TPA) moiety were synthesized by nucleophilic aromatic substitution using 4-fluoronitrobenzene with p-toluidine and p-anisidine, respectively. From these diamine monomers, electroactive polyimides (PI)s were prepared by the chemical imidization of poly(amic acid) solutions, which were prepared with 4,4 -oxydiphthalic anhydride (ODPA). 1 H nuclear magnetic resonance and Fourier transform infrared spectroscopy confirmed that both PIs had been synthesized successfully. The measured inherent viscosity for ODPA-CH3TPA PI and ODPA-OCH3TPA PI was 0.42 and 0.49 dL/g, respectively. The glass transition temperatures for ODPA-CH3TPA PI and ODPA-OCH3PDA PI were 236 • C and 238 • C, respectively, and the thermal degradation temperature of both PIs was above 390 • C. The band gaps of ODPA-CH3PDA and ODPA-OCH3PDA were 3.00 and 2.72 eV, respectively. The oxidation onset potential E ox of ODPA-CH3PDA PI and ODPA-OCH3PDA PI from cyclic voltammetry was 0.73 V and 0.65 V, respectively. The highest occupied molecular orbital and lowest unoccupied molecular orbital values differed according to the groups substituted into the triphenylamine moiety. After applying a voltage, the absorption peak intensity at 723 nm and 752 nm for ODPA-CH3TPA and ODPA-OCH3TPA, respectively, increased. The electrical properties varied according to the chemical structure of synthesized diamines.

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