Ionic Poly(p-phenylene terephthalamide)s: Preparation and Characterization

摘要

The preparation and characterization of two types of ionic poly(p-phenylene terphthalamide) (PPTA) is described. A sufficient number of ionic groups were added to render modified PPTA soluble in dimethylsulfoxide (DMSO). In one type, a hydrogen atom of the amide group was replaced by an ionic propanesulfonate group. In the orther type, one of the hydrogen atoms on the phenylene ring was replaced by an ionic sulfonate group. The ionic PPTAs in DMSO showed an upturn in viscosity at very low concentrations that was characteristic of the polyelectrolyte behavior. Fourier transform infrared spectra of these samples were also studied. When the ionic group was attached at the end of the short propane side chain, the intensity of both the free and hydrogen-bonded N-H stretching mode was reduced compared with that of PPTA. Depending on the location of the ionic group, there some changes in the intensity and wave number of the acymmetric and symmetirc vibrations of the ionic SO_3~- group and the stretching mode of the carbonyl group. In both ionic PPTAs, there was an upward shift in the frequency of the symmetric vibrations of the sulfonate ion when the counterion, having been monovalent, became divalent.