Study Kinetics of Thermal Decomposition and Electrochemical Oxidation by Using Nanocomposite Paste of Novel Poly(amide-ether)s Derived from Asymmetric Diamine

Abstract

A new asymmetric diamine containing diarylimodazole pendant was synthesized from the nucleophilic substitution reaction of 1-fluoro-4-nitrobenzene and 2,4-dihydroxy benzaldehyde in the presence of K2CO3, followed by reaction with benzil and ammonium acetate for the preparation of imidazole ring. This novel diamine was used to prepare poly(amide-ether) (PAE) in reaction with different commercially available dicarboxylic acids via direct polycondensation using triphenyl phosphite and pyridine (Py) as catalyst. The PAEs were fully characterized and their properties such as inherent viscosity, solubility, optical, thermal and kinetics of thermal decomposition, and electrochemical oxidation were investigated. The polymers had inherent viscosity in the range of 0.47–0.65 dL/g and were noncrystalline with excellent solubility in various polar aprotic organic solvents. Their Tg values ranged from 200 to 355°C and 10% weight loss temperature above 450°C in nitrogen and left more than 70% residue at 650°C. The kinetic parameters of thermal degradation such as activation energy, entropy, enthalpy and Gibbs free energy of thermal decomposition have been evaluated using different equations. We also report electrochemical oxidation of the resulting polymers in aqueous solution by using cyclic voltammetry technique on the multi-walled carbon nanotube-modified glassy carbon electrode.