2,5-Thiophene-based liquid crystalline poly(amide)s, poly(arylene ether ketone)s, and poly(benzimidazole)s.

摘要

Poly(p-phenylene terephthalamide) (PPTA or Kevlar;PPThA lyotropic solutions are studied using deuterium NMR spectroscopy. LC solutions may be aligned in a magnetic field to yield a "single liquid crystal"--a macroscopically orientated phase. In such uniaxial solutions, the transition to isotropic state at elevated temperatures may be indirectly monitored by deuterium NMR; quadrupolar interactions of the probe molecule (deuterated sulfuric acid) reflects changes in the macromolecular ordering. Direct monitoring of polymer order is accomplished using deuterium labeled PPThA (deuterated on the p-phenylene ring of the diamine). Deuterium NMR lineshapes simulation programs (written by Dr. C.-D. Poon) enable us to reproduce changes in the NMR spectra that correspond to the nematic director reorientation experiments wherein aligned samples are rotated in the magnetic field.;Realizing that the high-performance properties of the thiophene-based polyamides are being maintained with the added benefits of enhanced processibility, we decided to introduce thiophene units into poly(arylene ether ketone)s and poly(benzimidazole)s. High molar mass polymers are synthesized and characterized.