ENHANCEMENT OF DIMENSIONAL STABILITY IN SOLUBLE FLUORINATED POLYIMIDES VIA THE IN-SITU FORMATION OF LANTHANUM(III)-OXO-POLYIMIDE NANOCOMPOSITES

The synthesis and characterization of composite inorganic-polyimide fi lms is described by adding diaquotris(2,4-pentanedionato)lanthanum(III ) to soluble, low dielectric, colorless polyimides formed from 2,2-bis (3,4-dicarboxyphenyl)hexafluoropropane dianhydride/1,3-bis(3-aminophen oxy)benzene (6FDA/APB), and 6FDA/2,2-bis[4-(4-aminophenoxy]hexafluorop ropane (6FDA/BDAF). The [La(acac)(3)(2H(2)O)(2)]-containing polyimide films were thermally treated from 220 to 340 degrees C which resulted in substantial lowering of the linear coefficients of thermal expansio n at low metal concentrations (< 4 %) without sacrificing other essent ial thermal and mechanical properties of the parent polyimide. TEM dat a are consistent with particle sizes for the lanthanum ion-containing species which are in the nanometer range; thus, the visual clarity of the films was maintained. Refractive index measurements indicate that the films are isotropic. Addition of the lanthanum complex to the poly (amic acid) form of 6FDA/APB and 6FDA/BDAF followed by thermal curing to 300 degrees C yields low molecular weight crazed polyimide films.