Langmuir-Blodgett films of poly alkyl thiophenes: Preparation and characterization of multilayers

The interfacial behaviour of poly alkyl thiophene monolayers formed at air/water interface have been studied using π-A isotherms. These formed stable condensed monolayers on water and could be transferred by the Langmuir-Blodgett (LB) technique. The UV visible spectra of the LB films showed that the polythiophenes form well-defined aggregates with their long axes nearly vertical to the layer plane. Optical microscopy in the Brewster angle set-up showed rigid striated structures in the case of hexyl-substituted polymer while the cyclohexyl derivative showed a less oriented monolayer. In the case of hexyl-substituted polymer (LB) films, the planar polythiophene main chains lie roughly edge-on parallel to the substrate while side chains are approximately orthogonal to the substrate.