Atomic force microscopy study of structural organization of carbosilane liquid crystalline dendrimer

Structural organization of a carbosilane liquid crystalline dendrimer of fifth generation with cyanobiphenyl mesogenic groups in the 25-130 degrees C range was examined by atomic force microscopy(AFM) Studies were performed on the dendrimer films of different thicknesses, from single macromolecular layers to films several micrometers thick. Packing motifs of spherical macromolecules (5.5 nm in diameter) were revealed in submicrometer AFM images of the dendrimer films. Rectangular and hexagonal lattices were found in the single layers on different substrates. With an increase of film thickness, first smectic layers are formed, and then domains consisting of aggregates of flat-on lying and edge-on standing smectic layers were found. In thick films, the domains exhibit layered structures of different thicknesses and with different orientations. AFM images recorded at different temperatures demonstrated height changes of different domains caused by anisotropic changes of lattices of the smectic layers.