Schiff Base-Substituted Polyphenol: Synthesis, Characterisation and Non-Isothermal Degradation Kinetics

Background: Polymers of phenols and aromatic amines have emerged as new materials in fields such as superconductors, coatings, laminates, photoresists and high-temperature environments. The stability, kinetics and associated pollution of the thermal decomposition of oligophenols are of interest for the aforementioned fields. Results: A new Schiff base polymer, derived from N,N\u27-bis(2-hydroxy-3-methoxyphenylmethylidene)-2,6-pyridinediamine, was prepared by oxidative polycondensation. Characterisations using Fourier transform infrared, UV-visible, 1H NMR and 13C NMR spectroscopy, thermogravimetric/differential thermal analysis, gel permeation chromatography, cyclic voltammetry and conductivity measurements were performed. The number-average (Mn) and weight-average molecular weight (Mw) and dispersity (D = Mw/Mn) of the polymer were found to be 61 000 and 94 200 g mol-1 and 1.54, respectively. Apparent activation energies of the thermal decomposition of the polymer were determined using the Tang, Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose and Coats-Redfern methods. The most likely decomposition process was a Dn deceleration type in terms of the Coats-Redfern and master plot results. Conclusion: The mechanism of the degradation process can be understood through the use of kinetic parameters obtained from various non-isothermal methods