Formation of liquid-crystalline-type structures in poly(paraamides)

It is shown that the sorption method makes it possible to quantitatively estimate the presence of ordered structures in the supramolecular structure of partially crystalline and liquid-crystalline paraamide polymers. Using 1H NMR spectroscopy and the sorption method, the growth of liquid-crystalline type structures during spinning and thermal treatment of the poly(paraamide) fiber is analyzed. A comparison of the 1H NMR spectra of the as-spun and heat-treated fibers at low temperatures (110–210 K) in a rigid lattice reveals that “loose” disordered microregions occur in the fiber before thermal treatment. Thermal treatment results in the “healing” of structural defects and leads to the appearance of liquid-crystalline-type structures owing to the large-scale quasi-segmental motion at a high temperature.