Synthesis and electrochemical properties of new redox-active polyimides with (1-piperidinyl)triphenylamine moieties

A series of new electroactive aromatic polyimides with (1-piperidinyl)triphenylamine moieties were prepared from 4,4-diamino-4-(1-piperidinyl)triphenylamine and aromatic tetracarboxylic dianhydrides via the conventional two-step polycondensation technique. Flexible and strong polyimide films could be obtained via the thermal curing of their precursor poly(amic acid) films. The polyimides showed high glass transition temperatures between 288 degrees C and 318 degrees C, and they did not show significant decomposition before 500 degrees C in air or nitrogen atmosphere. Cyclic voltammograms of the polyimide films on the indium-tin oxide-coated glass substrate exhibited a pair of reversible oxidation waves with low onset oxidation potentials of 0.45-0.49 V (vs. silver/silver chloride) in acetonitrile solution. Upon oxidation, the color of the polyimide films changes from pale yellow to yellowish green and finally to blue.