THE ADSORPTION OF ORDERED POLYIMIDE MONOLAYERS

Ordered polyimide monolayers can be prepared on solid surfaces using the Langmuir-Blodgett technique of Kakimoto and co-workers. In the present study we have investigated the adsorption of two different monolayers (PMDA-ODA and PMDA-PDA) on both graphite and oxidised silicon surfaces. Scanning tunneling microscopy indicates that on graphite both the rod-like PMDA-PDA and the zig-zag PMDA-ODA are characterized by a high degree of two-dimensional order. X-ray absorption near edge spectroscopy (XANES) at the carbon, nitrogen and oxygen K-edges has been used to obtain information on the orientation of the different moieties in the polymer chain. These XANES data are compared to the corresponding spectra of pyromellitic diimide and diphenyl ether, which may be regarded as the building blocks of PMDA-ODA polyimide, in order to obtain more insight into the origin of the resonances.