Ionic PPTAs and Their Molecular Composites and Amorphous Polar Polymers

摘要

Ionic PPTAs, in which ionic groups with various counterions are attached to mainchains, side chains, or both, have been made and their thermal properties are investigated. The salt-form ionic PPTA shows better thermal stability than the acid-form PPTA. Furthermore, it is found that thermal stability is closely related to the rigidity of the ionic PPTA molecules. We have also prepared homogeneous molecular composites in which rigid-rod molecules (ionic PPTA) are well dispersed in polar matrix polymers (PVP and S-AN) via ion-dipole interactions. The appearance of a single Tg, shifting to higher temperatures with increase in ionic PPTA content, and TEM morphological observations have indicated good dispersion of the rigid-rod ionic PPTA molecules. The deformation mode of the matrix polymer is modified significantly upon addition of rod molecules: e.g., an addition of ionic PPTA molecules into amorphous matrix polymers induces shear deformation. Mechanical testing shows enhanced toughness in addition to increased stiffness and strength for the molecular composites. Upon replacement of a monovalent counterion to a divalent one, the composites develop more extended shear deformation zones under simple tension.