Langmuir-Blodgett (LB) films of the water-soluble
dye phenosafranine (PS) have been prepared by its adsorption from aqueous
dye solution to an
arachidic acid (AA) monolayer at the air-water interface. Atomic force microscopy (AFM) images of the LB films revealed the effect of change in pH of deposition on the degree of complexation of AA with the PS
dye. Well-defined circular islands and holes were observed which disappeared with the increase in pH. Polarized absorption studies indicated that the
dye molecules are oriented uniaxially with their long axis titled at a constant angle to the surface normal of the LB film. Within the restricted geometry of the LB film, the PS
dye was electropolymerized to form a two-dimensional film of poly(
phenosafranine) sandwiched between
arachidic acid layers. The film was characterized by IR spectroscopy, cyclic voltammetry, and AFM. X-ray diffraction studies reveal the presence of a layer structure in the AA-PS LB film before and after polymerization. The
polymer film showed highly anisotropic electrical conductivity of ca. 10 orders of magnitude. This indicates the formation of two-dimensional
polyPS layers between
arachidic acid layers resulting in a layered heterostructure film having alternate conducting and insulating regions. Also, the conductivity of the
polyPS prepared from LB film was found to be approximately 2.5 times higher than the conductivity of
polyPS prepared by
solution polymerization method.