Synthesis, characterization and comparative study of aromatic polyureas based on ۲, ۳-dihydro-۱, ۴-phthalazinedione with various aromatic and aliphatic diisocyanates

Rigid aromatic backbone in high-performance polymers such as Kevlar has been known to be effective in their remarkable properties. Four new polyureas were synthesized based on the ۲, ۳-Dihydro-۱, ۴-phthalazinedione with various aromatic and aliphatic diisocyanates to mimic the properties of high-performance polymers with accessible monomers, facile synthesis procedures, and more economic. The chemical structure of polyureas was validated using Infrared spectroscopy (IR) and elemental analysis. Molecular weight was determined using the Mark-Houwink equation. Weight losses of these polyureas with temperature were determined by thermal gravimetric analysis (TGA). Depending on the structure of polyureas, that had an average melting temperature of ۱۵۳-۲۹۰ °C, Solubility parameters were calculated using the group molar attraction constants of Hoy. Polymers were almost insoluble in different solvents, as demonstrated by attempts to solubilize in several solvents at ۴۰ °C.