Synthesis and characterization of polyimides from triphenylamine-based diamine monomers with thiophene or trifluoromethyl side group

Triphenylamine-based novel diamine monomers with side group, such as 4-(2,2′-bithiophenyl)-4′,4″-diaminotriphenylamine (2TTPA) and 4-(3,5-bis(trifluoromehyl)phenyl)-4′,4″-diaminotriphenylamine (6FTPA) were prepared and used for polyimide synthesis. 4-Bromo-dinitrotriphenylamine (BrTPA), prepared from 4-bromoaniline and 1-fluoro-4-nitrobenzene, was reacted with 2,2′-bithiophenene-5-boronic acid (2TBB) or 3,5-bis(trifluoromethyl)benzeneboronic acid (6FBB), followed by hydrogenation to afford 2TTPA and 6FTPA, respectively. After characterization by FT-IR, 1H-NMR, EA and melting point analyzer, the triphenylamine-based dimaines were utilized to prepare polyimides with 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) or 2,2-bis-(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA). The polymers were characterized by FT-IR and 1H-NMR. Thermal, optical and electrical properties were also evaluated by DSC/TGA, UV–vis/photoluminescence spectrometery and cyclic voltammetry (CV), respectively. The 6FDA–6FTPA polyimide exhibited high glass transition temperatures (291°C), high thermal stability (>488°C) and light blue emission (480nm) with very good solubility even after imidization.