Influence of Hydrogen-Bonding Interaction Introduced by Filled Oligomer on Bulk Properties of Blended Polyimide Films

Specific structure oligomer is designed and synthesized to fill blank interaction points left among polyimide (PI) rigid-rod structure in order to further enhance the interaction between PI macromolecules. An oligomer, 4,4-bisbenzamide diphenyl ether (BADE) containing amide groups as proton donor, was blended with polyamic acid (PAA) solution to modify PI of pyromellitic dianhydride and 4,4-oxydianiline. Fourier transform infrared and dynamic mechanical analyses show that hydrogen-bonding interaction occurs between NH groups and PI chains. This resulted interchain interaction increases the tensile strength of blended PI films from 115.9 to 135.6 MPa, about 17.0% improvement, with BADE content surprisingly up to 20 wt %. BADE is uniformly dispersed without aggregation within a saturated amount of 20 wt % through wide angle X-ray diffraction and morphology characterization. Moreover, rheological measurements indicate that the processability of PAA solution is maintained after introduction of BADE. The obtained PI films still have excellent thermal stability. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40498.