Study on preparation and properties of novel reactive phenolic hydroxyl-containing polyimides

Novel reactive polyimides (PIs) containing phenolic hydroxyl functionalities were prepared from 4-(4-hydroxyphenyl)-2,6-bis[3-(4-aminophenoxy)phenyl]pyridine (m,p-HAPP) with various aromatic dianhydrides via one-step polycondensation procedure. The inherent viscosities of the PIs were 0.54–0.63 dL/g in DMF solution and most of them were readily soluble in common organic solvents such as DMF, DMAc, NMP, and m-Cresol, etc. Meanwhile, the PIs also had good thermal stability, with the glass transition temperature (T _g) of 221.7–310.5 °C, the temperature at 10 % weight loss of 524.1–579.3 °C in nitrogen atmosphere. Then commercial epoxy resin was cured in the presence of different ratios of the reactive polyimide, giving a series of polyimide modified epoxy films. Thermogravimetric analysis showed the increase of the temperature at 5 % weight loss of the films with the increase of the polyimide content; 296 °C for 0 %, 309 °C for 1.95 %, 337 °C for 3.85 % and 350 °C for 5.63 %.