PPTA anion shows polyelectrolyte behaviour in solution and birefringence in film specimens, reflecting rigid conformation of backbone chains. The PPTA anion was blended with a flexible-coil polymer, poly(vinylpyridine) to make molecular composites. Optical clarity, polarizing optical microscopy, and dynamic mechanical thermal analysis all indicate the formation of homogeneous molecular composites for the PPTA anion/poly(4-vinylpyridine) system having up to 2 wt% of PPTA anion. These molecular composites show no phase separation upon heating, indicating that they are melt-processable. Ion-dipole interactions formed between ionic groups of the PPTA anion and ionic dipoles of vinylpyridine groups are responsible for good miscibility. The change of the matrix polymer to poly(2-vinylpyridine) leads to some phase separation, as a result of decreased miscibility due to steric hindrance.