Self-organizing fiberlike nanostructures and wrapping-up processes in Langmuir-Blodgett films

Fiberlike supramolecular structures, almost monodisperse in diameter (14 +/- 2 nm), were obtained in quercetin-3-O-palmitate (QP) Langmuir-Blodgett monolayers transferred on solid substrates by working at a relatively high subphase temperature (37 degreesC) and surface pressure (30 mN/m). The formation of QP fiberlike structures of similar diameter was also reached by exploiting phase separation processes occurring in mixed monolayers of dimyristoylphosphatidylcholine and QP at 10 degreesC. In the mixed films, the nanoscopic fibers were observed to curve and wrap up, leading to novel spirallike domains. The wrapping-up process was observed to be enhanced either by lowering the barrier compression speed at the air/water interface or by heating the solid support at the air/solid interface. The above phenomena were observed by scanning probe microscopy of the transferred monolayers. By employment of different operative modes including tapping, phase, friction, and the dynamic attractive regime, important insights on the phase separation as well as the mechanical properties of the nanostructures were found.