MONOLAYERS AND LANGMUIR-BLODGETT-FILMS OF POLY(N-ACYLETHYLENIMINES)

The behavior of poly(N-undecanoylethylenimine) of various molecular weights has been studied at the air-water interface by surface pressure-area measurements and high-sensitivity ellipsometry. The results indicate that this polymer can form stable monolayers on the water surface: at low surface pressures the polymer main chain lies flat on the surface while the side chains are in the air. As the monolayer is compressed to a critical point where the main chains are closely packed, the side chains orient themselves roughly perpendicular to the interface. This close-packing condition is the same for a wide range of molecular weights. Langmuir-Blodgett films of this polymer can be easily prepared by the vertical deposition method. The monolayers deposit as Y-type films, each 1.6 nm thick.