ENHANCEMENT OF DIMENSIONAL STABILITY IN SOLUBLE POLYIMIDES VIA LANTHANIDE(III) ACETATE ADDITIVES

Soluble lanthanide(III) acetate tetrahydrates have been added to dimet hylacetamide solutions of the soluble colorless polyimide 6FDA/3,3'-AP B formed from 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydrid e and 1,3-bis(3-amino-phenoxy) benzene to effect the isotropic lowerin g of the linear coefficient of thermal expansion (CTE) of the resultin g polyimide films. Thermal treatment of the doped films generates an i norganic lanthanide phase which consists of particles from 20-40 nm in the bulk of the film and lowers the CTE's up to 12 percent (relative to controls with the same thermal history). The thermal and mechanical properties of the doped polyimide films are retained. The films retai n the optical transparency of the parent polyimide.