Abstract: The microscopic molecular structure of a polyimide (PI) Langmuir-Blodgett (LB) film monolayer was studied by atomic force microscopy (AFM).An AFM image of a PI monolayer on highly oriented pyrolytic graphite (HOPG) showing clearly the polymer chains was observed. The measured parameters in situ,for example,the distance between oxygen atoms at successive bends is 1.4nm~1.9 nm and the bend angle is about 118 deg.,correspond with those from STM results by the others.The procedure in which the PA3S (polyamie acid alkyl amine salt) film was converted to polyimide film by either the heating method or the solution method is very important.The preliminary results of comparing these two technological processes observed by AFM indicated that the solution method is more suitable for this PI LB film preparation in the usage of the future liquid-crystal display devices.

Key words: Langmuir-Blodgett (LB) films, long chain orientation, aligning layer, Polyimide (PI)