Molten Tetrabutylammonium Bromide as Eco-Friendly Media for the Synthesis of Novel Optically Active and Thermal Stable Polyamides under Microwave Irradiation
The present paper is an extension of microwave method describing the synthesis of optically active polyamides (PAs). The main focus of this work is the design of effective microwave method for preparing of optically activePAs. The diacid containing amino acid and 1,8-naphthalimide group was prepared in three steps. For the preparation of optically active polymers from this monomer the polycondensation reactions of diacid 7 with different aromatic and aliphatic diisocyanates was employed in the presence of a small amount of tetrabutylammonium bromide as ionic liquid media that acts as a primary microwave absorber and was compared with conventional heating. The resulting polymers were characterized using FT/IR, 1H NMR, 13C NMR, UV-vis spectroscopy, fluorimetry, specific rotation techniques and elemental analysis. Thermal properties of the resulting PAs were evaluated by thermogravimetric analysis and differential scanning calorimetry. The interpretation of kinetic parameters (E, ΔH, ΔSand ΔG) of thermal decomposition stages have also been evaluated using Coats-Redfern and Dharwadkar-Kharkhanawala equations.