DEPENDENCE OF LANGMUIR-BLODGETT-FILM QUALITY ON FATTY-ACID MONOLAYER INTEGRITY .1. NUCLEATION CRYSTAL-GROWTH AVOIDANCE IN THE MONOLAYER THROUGH THE OPTIMIZED COMPRESSION PROCEDURE

A rational approach for avoiding defects in fatty acid monolayers is exposed. It is demonstrated that the early stages of compression affect the integrity of a behenic acid monolayer prior to transfer. It was shown that defects such as crystals appeared in the monolayer and evolved in heaps when the monolayer is aging. This influences the quality of LB films as shown when transferring the monolayer onto three successive substrates. It is pointed out that the kinetics of appearance of crystals depends not only on the surface pressure but also directly on the way of compression. During this latter step, this evolution can be limited if a local surface overpressure is avoided. A study at different surface pressures in solid phase suggests that the nucleation crystal growth may be a triggering mechanism of slow collapse.