Influence of the monolayers composition on bilayer formation during oblique drop impact on liquids

We study the dynamics of two phospholipid monolayers brought into contact by oblique drop impact on a liquid surface and bilayer/multilayer formation. Drop impact without monolayers shows that for low impact angles (α < 23°) and low drop velocities the drop spreads as a thin sheet on the target liquid without immersion and mixing of the two liquids. When drop and target liquid surface are covered with monolayers, bilayer/multilayer formation is expected. The composition and mechanical properties of the monolayers can strongly influence the pattern of drop impact and bilayer/multilayer formation. Monolayers with either pure saturated or unsaturated phospholipids, and their mixtures with cholesterol were used. We show that under all conditions studied bilayer/multilayer synthesis takes place. Asymmetric bilayers can be produced by the coupling of drop and target monolayers. For some lipid mixtures the drop and target monolayer collapses during drop impact and symmetric bilayers/multilayers are formed.