Synthesis and properties of aromatic polyimides derived from 2,7-triptycenediamine

Novel aromatic polyimides were synthesized from 9,10-dihydro-9,10-o-benzenoanthracene-1,5-diamine (2,7-triptycenediamine) and aromatic tetracarboxylic dianhydrides. The polymerization was carried out in a two-step procedure including ring-opening poly-addition giving polyamic acids, followed by thermal cyclodehydration. The polyamic acids have high inherent viscosities (0.97-1.95 dL/g in 1-methyl-2-pyrrolidone). The polyimides show high glass transition temperatures (392-409 degrees C), high decomposition temperatures at 5% weight loss (516-566 degrees C), and high weight residues (64-69% at 800 degrees C). All polyimides are amorphous. The polyimide from the diamine with 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (4,4'-sulfonyldiphthalic anhydride) is soluble in pyridine, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide and cone. sulfuric acid at 60 degrees C, and shows high thermal stability. The introduction of 2,7-triptycenediyl structure into the polyimide backbone has the effect of improving the solubility and maintaining the high thermal stability.