Syntheses and characterizations of cardo polyimides based on new spirobifluorene diamine monomer

Abstract We synthesized a new spirobifluorene diamine monomer, 2,7-diamino-9,9-spirobifluorene (2,7-DASBF), in which two fluorene units are perpendicularly linked by the ‘spiro’ sp 3 carbon, and two diamine groups are attached on the same fluorene ring. Two cardo polyimides were prepared from the polymerization of 2,7-DASBF with 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (PI-1) or pyromellitic dianhydride (PI-2). The chemical structures of monomer and polymers were characterized by various spectroscopic techniques. Thermal stability, coefficients of thermal expansion and crystallinity of the resulting polyimides were investigated.