MICROSTRUCTURE OF THIN LANGMUIR-BLODGETT-FILMS OF DIPALMITOYLPHOSPHATIDYLCHOLINE - ELECTRON-MICROSCOPIC IMAGES REPLICATED WITH PLASMA-POLYMERIZED FILM BY GLOW-DISCHARGE

Electron-microscopic images of 1- and 5-monolayer LB films of dipalmit oylphosphatidylcholine, transferred to a glass substrate at various su rface pressures encompassing the plateau region of the surface pressur e-area isotherm, were observed by using a plasma polymerization replic a method. One-monolayer films are flat and there is no substantial evi dence of structural defects up to the high surface pressures. Crystall ine domain structures appear in the 5-monolayer films even at the low surface pressures below the plateau, which accords well with our previ ous spectroscopic results. The domains decrease their size with increa ses in surface pressure and finally disappear at the high surface pres sures above the plateau. These are explained by the formation of a clo sely packed homogeneous structure around the plateau region. Further c ompression of the monolayer before the collapse pressure leads to the reappearance of the inhomogeneous crystalline domain structures, due t o the local collapse of the monolayer just before the main collapse pr essure.