SURFACE-STRUCTURE AND ORIENTATION OF POLYAMIC ACID ALKYLAMINE SALT LANGMUIR-BLODGETT-FILMS HAVING AN AZOBENZENE PENDANT UNIT

The structure of polymeric Langmuir-Blodgett (LB) films was studied by scanning force microscopy (SFM), Fourier transform infrared spectrosc opy (FTIR) spectroscopy, and second harmonic generation (SHG) measurem ents. Polyamic acid alkylamine salt LB films, having an azobenzene pen dant unit, were prepared by mixing the polyamic acids with single-chai n alkylamines or multichain alkylamines. When the single-chain alkylam ine was used, the SFM image of the LB film showed an island-like struc ture. The formation of the islands was attributed to a self-aggregatio n of the alkylamines in the LB film. FTIR and SHG measurements suggest ed that the single-chain alkylamines in the LB film had a poor orienta tion, and the azobenzene units had a tilt angle of 45.3 degrees from t he surface normal. On the other hand, the LB films having multichain a lkylamines exhibited a well-ordered orientation. The surface structure was observed uniform and there existed few defects in the SFM images. The multichain alkylamines were oriented approximately perpendicular to the surface plane, and the azobenzene unit had a tilt angle of 39.8 degrees.