Orientation Studies of LB Films

ORIENTATION STUDIES OF LB FILMS FABRICATED WITH SURFACE ACTIVE PYRROLES AND POLYPYRROLE. The molecular organizations of multilayer thin films of the surface active pyrrole derivatives used to formed mixed monolayers with electrically conductive polypyrrole chains and ferrocene derivatized pyrroles have also been examined by FTIR reflection/absorption techniques. The materials investigated in 

Fl lR studies of LB films fabricated fixjm alkyl substituted pyrroles were first carried out on Y-type films of 3-hexadecyl pyrrole [27]. These studies revealed that the pyrrole rings in films containing five monolayers are oriented vertically with respect to the plane of the substrate and the hydrocarbon tail groups are oriented approximately normal to the substrate. In the case of a single monolayer, however, the hydrocarbon tails were found to be tilted away from the substrate normal. It was speculated that this later effect is due to an 

The bilayer stacking distance obtained from low angle x-ray scattering measurements made on multilayers of 3-ODOP was calculated to be about 28 A. Hiis suggests that each monolayer is only about 14 A thick. To achieve this particular bilayer stacking, the fully 

An analysis of the vibrational bands associated with the electrically conducting polypyrrole chains (spectral region not shown) has further demonstrated that the polymer chains are preferentially oriented with the long axis of their fully extended backtones contained within the plane of the substrate. All of these observations are consistent with a structure in which the polypyrrole chains are sandwiched between oriented bUayers of the surface active pyrrole. X-ray diffraction analysis, however, also shows that a small portion of the multilayer film is comprised of separate molecul stacks of 3-octadecanoyl pyrrole molecules packed with their normal bilayer repeat distance. This suggests that some of the surface active pyrrole molecules under a reorganization during film transfo to form isolated molecular domains. Nevertheless, the primary stracture of Ae electrically conductive LB films is comprised of polypyrrole chains isolated between layers of the surface active pyrrole molecules. 

The NEXAFS technique is element specific and represents interactions with the nearest neighbor atoms. This property can be used to determine the orientation and electronic properties of individual moieties in a multicomponent system. For example, the sulfur L edge spectra in polythiophene systems or the nitrogen K edge spectra in polypyrrole 

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