The influence of rigid and flexible monomers on the physical‐chemical properties of polyimides

This article presents the synthesis and characterization of polyimides and copolyimides derived from rigid [4,4′‐(9‐fluorenylidene)dianiline (FNDA) and 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA)] and flexible segments [4,4′‐(1,3‐phenylenedioxy) dianiline (PDODA) and ethylenediaminetetraacetic dianhydride (EDTAn)], by polyaddition followed by thermal imidization of the polyamic acid. It describes the characterization of the polyimides and the polyamic acids in accordance to 1H NMR, FTIR, GPC, and XRD analysis, as well as solubility, mechanical (DMTA and stress–strain tests), thermal (DSC and TGA), and electric properties. Among the homopolymers, FNDA–BPDA and PDODA–BPDA form free‐standing films. The first presents higher Tg, thermal stability and Young's modulus. To tailor the properties copolyimides of FNDA, PDODA, and BPDA were synthesized. Young's modulus, Tg, thermal stability, dielectric constant, and solubility progressively increase with increasing amount of FNDA. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40351.