Synthesis and properties of novel polyaspartimides from 2,7-bis(4-maleimidophenoxy)naphthalene and aromatic diamines

A new aromatic bismaleimide containing bis(phenoxy)naphthalene unit, 2,7-bis(4-maleimidophenoxy)naphthalene, was synthesized from 2,7-bis(4-aminophenoxy)naphthalene and maleic anhydride by the usual two-step procedure that included ring-opening addition to give bismaleamic acid, followed by cyclodehydration to bismaleimide. The monomer was characterized by IR, H-1-NMR, EA and mass spectrometry. In addition, a series of polyaspartimides containing a naphthalene unit in the polymer backbone were prepared by the polyaddition of this bismaleimide and various diamines via a Michael-type addition in m-cresol with glacial acetic acid as a catalyst. The polymers were characterized by EA, IR and inherent viscosity. They were amorphous and soluble in various organic solvents such as N-methylpyrrolidone, DMAc, DMF, DMSO. Dark-brown and brittle films were obtained by casting from NMP or DMAc solutions. The glass transition temperatures of the polyaspartimides were in the range of 192-231 degrees C, and the 5% weight loss temperatures were above 300 degrees C in nitrogen.