DIRECT DEPOSITION AND CHARACTERIZATION OF LANGMUIR-BLODGETT MONOLAYERS OF SOLUBLE POLYIMIDES

Langmuir-Blodgett (LB) monolayers of three kinds of soluble polyimides were prepared with the direct deposition method, The monolayer struct ures were characterized with W-vis absorption spectroscopy, the wide a ngle X-ray scattering method and electrochemical techniques. The polyi mide molecules in the LB monolayers lie orderly on the substrate surfa ces with the orientation in which the dianhydride group is normal to t he substrate surface and two carbonyl oxygen groups close to the surfa ce. Therefore, the thickness of the three kinds of polyimide LB monola yers are the same because it depends on the distance between the two c arbonyl oxygen groups in the same ring. The area of monomeric units ar e dependent on the length of the diamine group. The model of the molec ular packing proposed from the quantomechanical calculation is in good agreement with the experimental results. (C) 1997 Elsevier Science S. A.