Solvatochromism effect and electrochemical activity of the solution-processable triazine-based polyimides

Abstract

A series of novel polyimides (PIs) containing solvatochromism characters were obtained by combining pyromellitic dianhydride (PMDA) and five triazine-based diamines. The resultant PIs showed desirable solubility in Lewis base solvent, which laid the foundation for preparation of solution-processable PIs and succeeding experiments. The cyclic voltammetry behavior of the resultant PIs reveals broad prospect for the application as the candidate materials of n-type semiconductor, which was corresponding to the result of quantum simulative calculation by Gaussian03 software. Opposite solvatochromism effects were displayed for the reason of the different acid–base property of acetonitrile (CH3CN) and 1-methyl-2-pyrrolidinone (NMP). The solution protonated by p-toluene sulfonic acid also make a greater contribution to the PI–CH3CN solutions rather than the PI–NMP solutions, which reveals their utilization potentiality for proton sensors. Before these works, X-ray diffraction (XRD) measurement was used to calculate the crystal size of the resultant PIs, which was also proved in the results of solubility testing. Besides, thermogravimetric analysis and differential scanning calorimetry were used to exhibit the amorphous or semicrystalline structure of the resultant PIs.