Fabrication of polyimide composite film with both magnetic and surface conductive properties

摘要

Bilayer polyimide film with superparamagnetic response and conductive surface has been exploited as an important candidate for electromagnetic interference shielding material. Polyimide matrix was derived from 4,4'-oxydianiline and 3,3',4,4'-benzophenonetetracarboxylic dianhydride. Iron (Ⅲ) 2,4-pentanedionate (Fe(acac)_3) and (1,1,1-trifluoro-2,4-pentadionato) silver(Ⅰ) (AgTFA) were chosen as magnetic nanoparticles precursor and silver source, respectively. At magnetic polyimide layer, in situ method allowed the Fe(acac)_3 to decompose to γ-Fe_2O_3, exhibiting typical superparamagnetic response. The conductive surface-silvered polyimide layer was prepared via in situ single-stage self-metallization technique by thermal curing of the AgTFA-contained poly(amic acid). The reduction of silver(Ⅰ) and further aggregation of silver atoms gave the conductive polyimide surface. The surface square resistance for the bilayer film of 0.1 Ω/square could be obtained. The structure and the properties of final bilayer film were characterized by X-ray diffraction, scanning and transmission electron microscope, magnetic and conductive measurements.