Synthesis and properties of processable poly(benzimidazole-imide)s based on 2-(3-aminophenyl)-5-aminobenzimidazole

A series of poly(benzimidazole-imide)s (PBIPIs) derived from different dianhydrides and 2-(3-aminophenyl)-5-aminobenzimidazole ( m -BIA) were synthesized via thermal imidization to form flexible films. This series of PBIPIs showed great T g s ranging from 296 to 484 °C, excellent thermal stability performed in 5% weight loss temperatures ( T d5% s) of 502–529 °C in N 2 and good mechanical properties (tensile strengths of 89–127 MPa, tensile moduli of 2.9–4.1 GPa and elongations at break of 3.9–6.9%). Compared with PIs derived from 6-amino-2-(4-(4-aminophenoxy)phenyl)-1H-benzimidazole ( p -BIODA), m -BIA based PBIPI films exhibited higher T g , and better solubility. Besides, the thermoplastic PBIPI resin (PI-6-PA) derived from 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA) and m -BIA exhibited good melt processability with high T g of 273 °C, melt flow index (MFI) of 7.76 g/10 min, minimum complex viscosity of 11.9 × 10 3  Pa·s at 402 °C and low melt viscosity ratio of 2.46 at 400 °C.