Crystal structure and thin film morphology of BBL ladder polymer

Summary form only given. Poly[7-oxo-7H-benz(d,e)imidazo(4',5':5,6)-benzimidazo(2,1-a)isoquinoline-3,4:10,11-tetrayl)-10 carbonyl (BBL) has drawn much attention due to remarkable electronic, optoelectronic and non linear optical properties. The polymer, like other rigid-rod polymers of poly(p-phenylene henzobisthiazole) (PBT) and poly(p-phenylene benzobisthiazole) (PBT), consists of rigid backbone with an extended /spl pi/-conjugation along the polymer backbone. But the polymer has a much larger molecular plane of ladder-like structure. Recently we reported that the rigid-rod PBT molecules form a unique self-assembled anisotropic structure in the polymer thin films: the molecular plane (a-axis) of the polymer chain is lying perpendicular to the film surface while the chain axis (c-axis) is in the film surface plane. In this presentation we report our recent results of BBL thin film morphology, showing the similar anisotropic assembly to that of PBT. The unique structure, however, appears to be very sensitive to the processing conditions and the polymer loses such anisotropy upon extrusion. We will also discuss the crystal structure of BBL polymer determined from the fiber.