Syntheses and properties of organosoluble polyimides based on 5,5?-bis[4-(4-aminophenoxy)phenyl]-4, 7-methanohexahydroindan

Abstract

A series of organosoluble aromatic polyimides (PIs) was synthesized from 5,5'-bis[4-(4-aminophenoxy)phenyl]-4,7-methanohexahydroindan (3) and commercial available aromatic dianhydrides such as 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 4,4'-oxydiphthalic anhydride (ODPA), 4,4'-sulfonyl diphthalic anhydride (SDPA), or 2,2'-bis(3,4-dicarboxyphenyl) hexafluoropropanic dianhydride (6FDA). PIs (III c-f ), which were synthesized by direct polymerization in m-cresol, had inherent viscosities of 0.83-1.05 dL/g. These polymers could easily be dissolved in N,N'-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), pyridine, m-cresol, and dichloromethane. Whereas copolymerization was proceeded with equivalent molar ratios of pyromellitic dianhydride (PMDA)/6FDA, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA)/6FDA, or BTDA/SDPA, or 1/2 for PMDA/ SDPA, copolyimides (co-PIs), derived from 3 and mixed dianhydrides, were soluble in NMP. All the soluble PIs could form transparent, flexible, and tough films, and they showed amorphous characteristics. These films had tensile strengths of 88-111 MPa, elongations at break of 5-10% and initial moduli of 2.01-2.67 GPa. The glass transition temperatures of these polymers were in the range of 252-311°C. Except for III e , the 10% weight loss temperatures (T d ) of PIs were above 500°C, and the amount of carbonized residues of the PIs at 800°C in nitrogen atmosphere were above 50%.