The procedure for preparing the LB film is as follows:
1. A solution of polyamic acid in a concentration of 1 mmol / L in DMAC and benzene and a similar solution of long chain fatty amine having the same concentration were mixed. To give a solution of the polyamic acid salt. Or a 1 mmol / L solution of the polyamide grease in a suitable solution.
2. The resulting solution was added to deionized water to form a stable monolayer film on the water surface.
3. The monolayer film is transferred onto a substrate such as glass, quartz or silicon.
4. The LB film of a polyamide acid salt or a polyamide resin which is supported on a substrate in a single layer or a plurality of layers is heated and polyimideized to obtain a polyimide LB film.