Homogeneous polyimide films with increased bis(N,N'-disalicylidene-1,2-phenylenediaminato)zirconium(IV) content

Abstract

To increase the concentration of inorganic component in polyimide films and enhance the materials' resistance to atomic oxygen, the complex (4-amino-N,N'-disalicylidene-1,2-phenylenediaminato)(N,N'-disalicylidene-1,2-phenylenediaminato)zirconium(IV), Zr(adsp)(dsp), was synthesized and allowed to react with poly(maleic anhydride) (PMA). The resulting Zr-PMA pendent polymer was mixed with a commercially available polyamic acid of pyromellitic dianhydride and 4,4'-oxydianiline (PMDA-ODA) in various proportions in NMP. Films were then cast onto glass substrates, and thermally imidized. The new mixed ligand complex and the Zr-PMA polymer were characterized by TLC, IR, 1H NMR, and elemental analysis, along with X-ray crystallography for the former and TGA for the latter. The imidized films of the Zr-PMA polymer blended with PMDA-ODA polyimide were studied by optical examination of multilayer film samples for crack formation, and SEM photography before and after atomic oxygen erosion in a plasma asher. The upper limit of Zr complex incorporation onto prebaked poly(maleic anhydride) was approximately 24% (mol of Zr/mol of repeat units). The upper limit of zirconium complex concentration for the Zr-PMA/PMDA-ODA blends, above which films crack upon imidization, was 8 mol %, compared to 4 mol % for mixtures of Zr(dsp)2 in PMDA-ODA polyimide.