MORPHOLOGY AND MOLECULAR ORDERING IN LANGMUIR-BLODGETT-FILMS FROM LADDER POLYHETEROARYLENES

We discuss features of the surface morphology and molecular ordering o f Langmuir-Blodgett (LB) films from complexes of poly(naphthoylene ben zimidazole) precursor and stearic acid. The anisotropic shape of the r igid ladder polymers with conjugated backbones promotes high in-plane ordering of the macromolecules during formation of LB films. Atomic fo rce microscopy, complemented by X-ray measurements, was used for chara cterization of the molecular ordering and surface morphology of LB fil ms on a wide range of scales. The surfaces of these LB films are very smooth, with microroughness of 0.3-0.6 nm for films consisting of four or five layers. On the molecular scale we observe wavy ridges aligned along the dipping direction, which corresponds to the direction of th e macromolecular backbones. The changes in surface morphology and rear rangement of the molecular backbones associated with thermal cyclizati on are discussed.