X-ray analysis of the structure of a copoly(ester-imide)

The structure of a thermotropic liquid crystalline copoly(ester-imide) prep ared from p-hydroxybenzoic acid (48 mol %), 4,4'-dihydroxybenzophenone (26 mol %), and N,N'-bis(trimellitimide)hexane (26 mol %) has been investigated by X-ray diffraction. X-ray fiber diagrams of as-spun and annealed fibers contain a series of aperiodic layer lines reminiscent of those seen for fib ers of other copolymers that have extended chain conformations and complete ly random monomer sequences. The positions of these layer lines were reprod uced approximately in simulation of the X-ray scattering by a fully extende d chain of completely random sequence, and the match was improved to within experimental error when we considered a stereochemically acceptable sinuou s chain. This agreement was lost when the sequence statistics deviated were completely random. (C) 1998 John Wiley & Sons, Inc.