Highly crystalline carbon films produced from benzimidazobenzophenanthroline ladder polymer

The carbonization behavior of benzimidazobenzophenanthroline ladder (BBL) polymer films has been investigated in comparison with those of polyoxadiazole (POD) and polyimide (PI) films. BBL polymer films could be carbonized while maintaining the smooth surface, whereas the surface of POD and PI films became uneven due to the formation of kinks and bumps, respectively. The carbonization yields of BBL polymer, POD and PI films at 2500°C were 64.1, 25.5 and 51.9%, respectively. Like POD- and PI-based carbon films, the carbon crystallites in BBL polymer-based carbon films were preferentially oriented so that the carbon layers are parallel to the film surface.