THERMOTROPIC LIQUID-CRYSTALLINE AROMATIC-ALIPHATIC POLYIMIDES .5. PREPARATION AND PROPERTIES OF HOMOPOLY(IMIDE-CARBONATE)S AND COPOLY(IMIDE-CARBONATE)S BASED ON BENZOPHENONETETRACARBOXYLIC DIIMIDE AND BIPHENYLUNITS

Melt polycondensation of N,N'-bis(3-hydroxypropyl)- or ,N'-bis(6-hydro xyhexyl)benzophenonetetracarboxylic diimide (n = 3 and 6) and/or 6,6'- (4,4'-biphenylylenedioxy)dihexanol with propylene or hexamethylene bis (phenyl carbonate)s (m = 3 and 6) afforded new semi-rigid homo- and co poly(imide-carbonate)s. The monomers for the polymerization, dihydroxy alkyl derivatives of imides, were prepared by a two-step reaction via intermediates, diacetates, from tetracarboxylic dianhydrides and 3-ami nopropyl- or 6-aminohexylalcohol. The structures of the expected monom ers and polymers were confirmed from FTIR and H-1- and C-13-NMR spectr um measurements and elemental analyses. Thermotropic liquid-crystallin e (LC) properties of the polymers were evaluated by differential scann ing calorimetry (DSC), polarizing microscopy and powder X-ray analyses at various temperatures. These measurements indicated that most polym ers except for a copolymer with a propylene segment (m = 3) based on t he benzophenonetetracarboxylic diimide of a hexamethylene spacer (n = 6) and the biphenyl unit showed birefringent melts. Only the copolymer having a hexamethylene spacer (n = 6) and a propylene segment (m = 3) formed a well-defined nematic LC phase. Measurements of viscoelastici ty with a thermomechanical analyzer showed that the poly(imide-carbona te)s possessed good mechanical properties.