SYNTHESIS AND CHARACTERIZATION OF SOLUBLE ALTERNATING AROMATIC COPOLYIMIDES

Aromatic alternating copolyimides have been synthesized by the reactio n of various precursors for imido diamine with 6FDA. The alternating c opolyimides appeared to have enhanced solubility in organic solvents s uch as N,N-dimethylacetamide (DMAc), N-methylpyrrolidinone (NMP), and dimethyl sulfoxide (DMSO) when compared with the corresponding random isomers. Various NMR experiments including 2-D COSY spectra have been performed for the characterization of the alternating copolyimides. On the basis of the NMR results, the synthetic pathway of the aromatic c opolyimide through the reaction of a precursor for imido diamine with a dianhydride leads to a copolymer with a complete alternating sequenc e without randomization during the cyclization reaction. The glass tra nsition temperatures of the alternating copolyimides obtained by DSC m easurements showed values similar to those of the corresponding random ones. The decomposition behavior obtained by TGA exhibited close degr adation temperatures of the alternating copolyimides regardless of the monomers used.