In-plane orientation controlled by a rotating disc in Langmuir and Langmuir-Blodgett films of a merocyanine dye

When a Langmuir film consists of mesoscopic domains having an elongated shape, stretching of the film due to Langmuir-Blodgett (LB) deposition and shearing due to a rotating disc can induce in-plane orientations of these domains. When the former governs the phenomenon, the domains are aligned perpendicular to the substrate surface (just before the transfer). When the latter governs the phenomenon, the domains are aligned along the concentric flow lines. We have studied the more complicated intermediate case by using two different molecular systems. It has been demonstrated that in LB films fabricated under such conditions, the orientation of the domains depends on the position on the substrate and the deposition type. Furthermore, monolayers deposited during the upward and downward strokes of the substrate become non-equivalent.