Synthesis and Characterization of Organosoluble Copolyimides Based on 3,3′,4,4′‐Diphenylsulfonetetracarboxylic Dianhydride and a Pair of Aromatic Diamines Containing 1,2‐Bis(4‐Aminophenoxy)‐4‐tert‐Butylbenzene

Abstract

AbstractA series of copolyimides was synthesized from commercial 3,3′,4,4′‐diphenylsulfonetetracarboxylic dianhydride with a pair of diamines, which contained 1,2‐bis(4‐aminophenoxy)‐4‐tert‐butylbenzene. The intermediate poly(amic acid)s had the inherent viscosities of 0.52–1.52 dL/g and were thermally converted into copolyimides. These copolymers were soluble in a variety of organic solvents such as NMP, DMAc, and DMF, and almost all of them could even be dissolved in less polar solvents such as m‐cresol, pyridine, and dioxane, showing a better solubility than corresponding homopolymers. Copolyimide films had tensile strengths of 87–160 MPa, elongations at a break of 9–12%, and initial moduli of 1.9–2.2 GPa. The glass transition temperatures of these copolymers were in the range of 262–288 °C, lower than that of homopolymers. The copolyimides had 10% weight loss temperatures in the range of 495–522 °C under nitrogen and 508–521 °C under air atmosphere, and they left more than 43% residue even at 800 °C in nitrogen. The thermal stability of copolymers was somewhat sacrificed due to the copolymerization, but they still belong under heat‐resistant polymeric materials.