Synthesis and Properties of Polyimides from Aromatic Dianhydrides Having Various Number of Phenylene Units and Bis{4-[4-(4-aminophenoxy)phenoxy]phenyl}Ether

摘要

A new para-substituted aromatic ether diamine, bis{4-[4-(4-aminophenoxy)phenoxy]phenyl} ether 1, was synthesized in four steps starting from 4,4’-dibromodiphenyl ether. New aromatic polyimides, with 5 ether linkages per monomer unit, were prepared from this diamine and various tetracarboxylic dianhydrides, pyromellitic dianhydride (PMDA), 3,3’,4,4’-biphenyltetracarboxylic dianhydride (DA-0), 3,3’’,4,4’’-p-terphenyltetracarboxylic dianhydride (DA-1), 3,3’’’,4,4’’’-p-quarterphenyltetracarboxylic dianhydride (DA-2), 3,3’’’’,4,4’’’’-p-quinquephenyltetracarboxylic dianhydride (DA-3), and 3,3’’’’’,4,4’’’’’-p-sexiphenyltetracarboxylic dianhydride (DA-4), by a conventional two-step procedure that included ring-opening polymerization in N-methylpyrrolidone (NMP) and subsequent thermal cyclic dehydration. The polyimides were characterized by wide-angle X-ray diffraction, differential scanning calorimetry (DSC), thermogravimetry (TG), and dynamic mechanical analysis (DMA). PI-PMDA from PMDA and PI-m (m = 0-4) from DA (m = 0-4) had glass transition temperatures (Tg) at 290 ℃ and 200-210 ℃, respectively. The thermal properties, adhesion properties heated at 400 ℃, dielectric constants (ε) and water absorption of the polyimides were compared and discussed on the basis of the number (m) of phenylene units in the dianhydrides.