Polymerization of 4‐(4′‐N‐1,8‐naphthalimidophenyl)‐1,2,4‐triazolidine‐3,5‐dione with diisocyanates

Abstract 4‐(4′‐Aminophenyl)‐1,2,4‐triazolidine‐3,5‐dione (1) was reacted with 1,8‐naphthalic anhydride (2) in a mixture of acetic acid and pyridine (3 : 2) under refluxing temperature and gave 4‐(4′‐N‐1,8‐naphthalimidophenyl)‐1,2,4‐triazolidine‐3,5‐dione (NIPTD) (3) in high yield and purity. The compound NIPTD was reacted with excess n‐propylisocyanate in N,N‐dimethylacetamide solution and gave 1‐(n‐propylamidocarbonyl)‐4‐[4′‐(1,8‐naphthalimidophenyl)]‐1,2,4‐triazolidine‐3,5‐dione (4) and 1,2‐bis(n‐propylamidocarbonyl)‐4‐[4′‐(1,8‐naphthalimidophenyl)]‐1,2,4‐ triazolidine‐3,5‐dione (5) as model compounds. Solution polycondensation reactions of monomer 3 with hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), and tolylene‐2,4‐diisocyanate (TDI) were performed under microwave irradiation and conventional solution polymerization techniques in different solvents and in the presence of different catalysts, which led to the formation of novel aliphatic‐aromatic polyureas. The polycondensation proceeded rapidly, compared with conventional solution polycondensation, and was almost completed within 8 min. These novel polyureas have inherent viscosities in a range of 0.06–0.20 dL g−1 in conc. H2SO4 or DMF at 25°C. Some structural characterization and physical properties of these novel polymers are reported.