Preparation and Characterization of HBPAA and HBPI Based on 6FDA and TTM
The amine end-capped HBPI [HBPI(6FDA-TTM)] made from 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) (Fig.
1] corresponding to the amide groups of the polyimide precursor (HBPAA) is absent in the HBPI spectrum.
x] in the membrane based on HBPI(6FDA-TTM) were considerably higher in comparison with those for HBPI based on 4,4'-oxydiphthalic anhydride and TTM  (33.
The products for which 10% or 20% of the imide groups of MI reacted with the amino groups of HBPI during the formation of amide linkages show a polyimide character (e.