Preparation of Polyimide/BaTiO3/Ag Nanocomposite Films via in situ Technique and Study of Their Dielectric Behavior

Triphase polyimide nanocomposite films were fabricated using barium titanate(BaTiO3) with high dielectric constant and silver(Ag) with high conductivity as fillers. In situ method was utilized to obtain the homogeneous dispersion of nanoparticles. The in situ polymerization of polyimide precursor-poly(amic acid) was performed in the presence of BaTiO3 particles. Silver compound 1,1,1-trifluoro-2,4-pentadionato silver(I) was added into the BaTiO3 containing poly(amic acid) solution to achieve silver nanoparticles via in situ self metallization technique. The thermally induced reduction converted silver(I) to metallic silver with concomitant imidization of poly(amic acid) to polyimide. Both BaTiO3 and silver nanoparticles were uniformly dispersed in the polyimide substrate. The dependence of dielectric behavior on the BaTiO3 and Ag contents was studied. The incorporation of small amount of silver nanoparticles greatly increased dielectric constant of composite films.