Head-to-head (H-H) linkages were observed in addition and condensation polymers. Pure H-H polymers of polyolefins, poly(vinyl halides), and polyacrylates were prepared, and the fundamental polymer properties were determined. They included mechanical, spectral, thermal, and degradation behaviors. These properties were compared with those of the traditional head-to-tail polymers. Blends of H-H polymers were also studied. The thermal and thermal-degradation behaviors of the blends were also investigated,