Accelerated Curing of Aryl−Ethynyl End-Capped Polyimide Oligomers and Model Compounds: A Kinetic Study Probing Substituent Effects

Abstract

The compounds N-phenyl-4-(10-methoxy-9-anthracenylethynyl)phthalimide (1), N-phenyl-4-(4-methoxy-1-naphthylethynyl)phthalimide (2), and N-phenyl-4-(4-benzonitrileethynyl)phthalimide (3) were synthesized to probe the effect(s) of electronic subsituents on the thermal curing of aryl−ethynyl end-capped oligomers using end-cap model compounds. The curing kinetics were analyzed using SEC and NMR techniques and Arrhenius parameters were determined and compared to the anthracenyl, naphthyl, and phenyl analogues, 4, 5, and 6, respectively. A thermal curing rate acceleration was attributed to the electron-donating methoxy functionality. This acceleration is independent from the previously observed rate acceleration (phenyl < naphthyl < anthracenyl). Analyses of product distribution of 95% cured model compounds via SEC reveal slight differences between 1 and 4 but no discernible differences between 2 and 5. The incorporation of the electron-withdrawing group has no effect on the thermal cure rates, as the curing ki...