The Influence of Rigid and Flexible Monomers on the Physical-Chemical Properties of Polyimides

摘要

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 T_g, thermal stability and Young's modulus. To tailor the properties copolyimides of FNDA, PDODA, and BPDA were synthesized. Young's modulus, T_g, thermal stability, dielectric constant, and solubility progressively increase with increasing amount of FNDA.