Syntheses and properties of poly (amide-imide)s based on 5,5′-bis[4-(4-trimellitimidophenoxy)phenyl]-hexahydro-4,7-methanoindan and aromatic diamines

Abstract

A novel polymer-forming diimide–diacid, 5,5′-bis[4-(4-trimellitimido phenoxy)phenyl]-hexahydro-4,7-methanoindan (II), was prepared by the condensation reaction of 5,5′-bis[4-(4-aminophenoxy)phenyl]-hexahydro-4,7-methanoindan with trimellitic anhydride. A series of novel aromatic poly(amide–imide)s (PAIs) containing polycyclic cardo groups was prepared by the direct polycondensation of II with various aromatic diamines using phosphorylation techniques. The polymers had inherent viscosities between 0.71 and 0.96 dl/g. The polymers were soluble in polar solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide (DMAc) and N,N-dimethylformamide, and could be cast from their DMAc solutions into transparent, flexible, and tough films, except for IIIa. These films had yield strengths of 85–114 MPa, tensile strengths of 77–102 MPa, an elongation at break of 8–17%, and initial moduli of 2.0–2.7 GPa. Wide-angle X-ray diffraction revealed that the polymers are amorphous. The glass-transition temperatures of the polymers were in the range 242–312 °C. All the PAIs exhibited no appreciable decomposition below 430 °C, and their 10%-weight-loss temperatures were in the range 484–507 °C in nitrogen and 494–515 °C in air.