forth in tables i and ii supra corresponding acid halides would be equally suitable reactants the following examples illustrate the method employed in preparing the polyimides in accordance with the invention to a stirred solution of 1 04 g 2 mmole of 2 2 bis 4 4 aminophenoxy phenyl hexafluoropropane in 4 0 g of dimethylacetamide was slowly added portionwise 0 645 g 2 mmole of benzophenone tetracarboxylic acid dianhydride btda at such a rate that each portion of dianhydride was allowed to dissolve before the next portion was added the reaction was run under a nitrogen blanket and was cooled with a wate bath the residual btda was washed into the reaction flasks with an additional 3 ml of dimethylacetamide to give a 19 percent by weight solids solution the reaction mixture was stirred for three hours after the last of the btda had been added and then was transferred to a vacuum oven the solvent was removed at 100 u00b0 c and the resulting amide acid polymer was imidized by heating it to 180 u00b0 c for 4 hours the tough flexible polymer was found to have an inherent viscosity of 0 47 dl g h 2 so 4 at 30 u00b0 c initial weight loss occurred at 420 u00b0 c in a tga scan in air using the same procedure as described in example ii a polyimide was prepared from 2 2 bis 4 4 aminophenoxy phenyl hexafluoropropane 0.