SPECTROSCOPY AND ELECTROCHEMISTRY OF LANGMUIR-BLODGETT-FILMS FORMED FROM RIGID ROD OLIGOIMIDES

Nine oligoimides with structures based on 1,4,5,8-naphthalenetetracarboxylic dianhydride (A) and 3,3'-dimethoxybenzidine (B) were synthesized and characterized. The end groups X on XPh-A-B-A-PhX were varied and the number of repeat units (therefore the length) was also changed. The longest oligoimide was B-A-B-A-B-A-B-A-B, a rigid rod 78 angstrom long. Applied to the water subphase of the Langmuir trough, pressure/area curves were recorded. Langmuir-Blodgett films were transferred by horizontal lifting to a variety of solid surfaces. The transfer ratios were 0.95 +/- 0.05. The transferred films were analyzed by UV, X-ray photoelectron spectroscopy, grazing angle reflectance IR, attenuated total reflectance IR, and transmission IR and were studied by cyclic voltammetry. In several cases anisotropic films were produced in which the average long molecular axis of the oligoimide was tilted up from the surface of the substrate by 10-25-degrees. In other cases the films were nearly isotropic. The structure and electrochemistry are compared to thin films of oligoimides formed by other methods.