Preparation and characterization of organosoluble copolyimides based on a pair of commercial aromatic dianhydride and one aromatic diamine, 1,4‐bis(4‐aminophenoxy)‐2‐tert‐butylbenzene,series

A series of copolyimides (co‐PIs) with high molecular weights, excellent mechanical properties, heat‐resistant properties, and good solubilities in organic solvents were synthesized from six kinds of commercial dianhydrides (IIa–f) and 1,4‐bis(4‐aminophenoxy)‐2‐tert‐butylbenzene (I). Monomers (IIa–d) for synthesizing insoluble PIs and monomers (IIe,f) for synthesizing soluble PIs were used to synthesize co‐PIs with arbitrary solubilities. Nine kinds of soluble co‐PIs (IIIa–e and IVa–d) were synthesized through chemical or thermal cyclodehydration. These co‐PIs were found to be easily soluble as well as able to be processed by casting from their solutions such as NMP, DMAc, m‐cresol, pyridine, THF, and CH₂Cl₂. The easily dissolved characteristics of this series of co‐PIs stemmed from the t‐butyl group and ether group within I. Besides, when the used dianhydride molecules contained the organosoluble groups, the solubilities in organic solvents could be greatly enhanced. The co‐PIs could improve the processability of polymers, while increasing their flexible mechanical properties and maintaining their excellent heat‐resistant properties. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 87–95, 2000