Synthesis, characterization and H2O2-sensing properties of pyrimidine-based hyperbranched polyimides

A series of hyperbranched polyimides having pyrimidine core in the backbone was prepared by solution polycondensation of pyromellitic dianhydride (A2 type) and 2,4,6-triaminopyrimidine (B3 type). The resulting polyimides were characterized by IR, GPC, DTA, DSC, TGA, density and viscosity measurement. The results showed that polyimides were obtained in 82-86% yield, had inherent viscosities of 1.58-1.87 dL/g and highly thermal stability. From the solubility tests, it was found that all the polyimides were soluble in NMP, DMAc and DMSO at room temperature. In addition, because of their interesting film properties, attempts were made to prepare H2O2-sensing polyimide material. For this reason, selectivity of film-coated electrodes obtained from the chemically prepared hyperbranched polyimides toward electroactive (ascorbic acid, oxalic acid and hydrogen peroxide) and non-electroactive (lactose, sucrose and urea) species was examined by means of CV, DPV and TB techniques. From the electrochemical data obtained, it has been demonstrated that polyimide (HPI-2) film responded to only hydrogen peroxide among the species examined. In other words, it has been claimed that the mentioned polyimide-coated electrode can be used as H2O2-selective membrane in the presence of the electroactive and non-electroactive interferents.