Journal of Polymer Science Part A: Polymer Chemistry, Vol.37, No.10, 1403-1412, 1999
Synthesis and characterization of new fluorene-based poly(ether imide)s
A novel bis(ether anhydride) monomer, 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride (4), was synthesized from the nitrodisplacement of 4-nitrophthalonitrile by the bisphenoxide ion of 9,9-bis(4-hydroxyphenyl)fluorene (1), followed by alkaline hydrolysis of the intermediate tetranitrile and dehydration of the resulting tetracarboxylic acid. A series of poly(ether imide)s bearing the fluorenylidene group were prepared from the bis(ether anhydride) 4 with various aromatic diamines 5a-i via a conventional two-stage process that included ring-opening polyaddition to form the poly(amic acid)s 6a-i followed by thermal cyclodehydration to the polyimides 7a-i. The intermediate poly(amic acid)s had inherent viscosities in the range of 0.39-1.57 dL/g and afforded flexible and tough films by solution-casting. Except for those derived from p-phenylenediamine, m-phenylenediamine, and benzidine, all other poly(amic acid) films could be thermally transformed into flexible and tough polyimide films. The glass transition temperatures (T-g) of these poly(ether imide)s were recorded between 238-306 degrees C with the help of differential scanning calorimetry (DSC), and the softening temperatures (T-s) determined by thermomechanical analysis (TMA) stayed in the range of 231-301 degrees C. Decomposition temperatures for 10% weight lass all occurred above 540 degrees C in an air or a nitrogen atmosphere.