ON THE NATURE OF POLYIMIDE CLAY HYBRID COMPOSITES

Polyimide-clay hybrid composites are formed by the intercalation of polyamic acid-dimethylacetamide (DMAc) solutions in CH3(CH2)n-1NH3+ montmorillonites (n = 4-18) and the subsequent thermal conversion of the polyamic acid to a polyimide. Owing to the concomitant displacement of the gallery onium ions by protons upon removal of the DMAc solvent, a single layer of polymer is intercalated (gallery height approximately 3.6 angstrom). Although layer aggregation is extensive and may involve formation of a fractal structure, the CO2 permeability of the composite (P(c)) relative to the pristine polymer (P(p)) is greatly decreased at loadings in the range 1.0-8.0 vol % clay.