Synthesis, characterization, thermal stability and electrochemical properties of poly-4-[(2-methylphenyl)iminomethyl]phenol

Abstract

In this study, the reaction conditions of poly-4-[(2-methylphenyl)iminomethyl]phenol (P-2-MPIMP) were studied by using oxidants such as air O 2, H 2O 2 and NaOCl in an aqueous alkaline medium between 50 and 90 °C. The structures of the synthesized monomer and polymer were confirmed by FT-IR, UV–vis, NMR and elemental analysis. The characterization was made by TG-DTA, size exclusion chromatography (SEC) and solubility tests. At the optimum reaction conditions, the yield of poly-4-[(2-methylphenyl)iminomethyl]phenol (P-2-MPIMP) was found to be 20% (for air O 2 oxidant), 33% (for H 2O 2 oxidant), and 74% (for NaOCl oxidant). According to the SEC analysis, the number-average molecular weight ( M n), weight-average molecular weight ( M w) and polydispersity index (PDI) values of P-2-MPIMP were found to be 3300, 4100 g mol −1 and 1.242, using H 2O 2, and 4550, 5150 g mol −1and 1.132, using air O 2 and 5300, 5850 g mol −1 and 1.104, using NaOCl, respectively. According to TG analysis, the weight losses of 4-[(2-methylphenyl)iminomethyl]phenol (2-MPIMP) and P-2-MPIMP were found to be between 75.29% and 48.17% at 1000 °C, respectively. P-2-MPIMP was shown to have a higher stability against thermal decomposition. Also, electrical conductivity of the P-2-MPIMP was measured, showing that the polymer is a typical semiconductor. Electrochemically, the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO) and electrochemical energy gaps ( E g ′ ) of 2-MPIMP and P-2-MPIMP were found to be −6.01, −6.03; −2.63, −2.82; 3.38 and 3.21 eV, respectively. According to UV–vis measurements, the optical band gap ( E g) of 2-MPIMP and P-2-MPIMP was found to be 3.40 and 2.97 eV, respectively.