SYNTHESIS, CHARACTERIZATION AND PROPERTIES OF POLYIMIDES FROM 3,3',4,4'-BENZOPHENONETETRACARBOXYLIC DIANHYDRIDE AND IMIDAZOLE-BLOCKED 2,5-BIS[(N-ALKYLOXY)METHYL]-1,4-BENZENEDIISOCYANATES

By the solution condensation of 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) with imidazole-blocked 2,5-bis[(n-alkyloxy)methyl]-1,4-benzene nates (C-m-BDIs) a series of aromatic polyimides (C-m-BP-PIs) having flexible (n-alkyoxy)methyl (-CH2O-n-CmH2m+1, = 4, 6, 8) side chains were prepared and characterized by IR- and H-1-NMR spectroscopy and their properties were measured and discussed in respect to the effects of side chains. Inherent viscosities of the polymers were in the 0.23 - 0.34 dL/g range. All the polymers were highly soluble in N,N'-dimethylpropyleneura(DMPU) and C-6- and C-8-BP-PIs even in CHCl3 at room temperature. UV-VIS spectra showed that the pi-electrons are delocalized along the main chain. TGA studies showed a two-step pyrolysis behavior and in DSC Tg's of C-4-, C-6- and C-8-BP-PIs were determined to be 184, 135 and 127 degrees C, respectively. Wide-angle X-ray diffractometry for as-polymerized samples revealed a quite low crystallinity with only loosely developed layered structure.