Synthesis and Characterization of Novel Aromatic Polyimides from Aromatic Diamine and 3,3''', 4,4'''-p-Quinquephenyltetracarboxylic Dianhydride

摘要

A new rigid tetracarboxylic dianhydride, 3,3"", 4,4""-p-quinquephenyltetracarboxylic dianhydride, was synthesized in seven steps starting from diethyl 4-bromophthalate. New aromatic polyimides containing a p-quinquephenyl unit were synthesized from this tetracarboxylic dianhydride and various aromatic diamines by the conventional two-step procedure of ring-opening polyaddition in a polar amide-type solvent and subsequent thermal cyclic dehydration. These polyimides had inherent viscosities of 0.20-1.20 dL g~(-1), and were insoluble in organic solvents. The polyimides were characterized by differential scanning calorimetry (DSC), thermogravimetry (TG), wide-angle X-Ray diffraction measurements, and dynamic mechanical analysis (DMA). Typical polyimides had glass transition temperatures (T_g) at about 250 deg C, and crystallized above T_gs. The effects of p-quinquephenyl structure were reflected in the high storage modulus above the glass transition temperature.