Fig. 6. Graphical illustration of the stages involved in the evolution of a liquid crystal film on graphite: A) surfactant monolayer; B) hemicylindrical micellar monolayer; C) vectorial nucleation of worm-shaped mesostructures: D) liquid crystal film; E) liquid crystal film with non-rigid outer zone. In this scheme it is important to realize that the boundary of this liquid crystal is uncertain and its definition is dependent on the way that it was measured (and perturbed).
(Fig. 6B). This is the case for all surfactant concentrations measured. However, worm-shaped mesostructures emerge at a surfactant concentration above approximately 9 mM and vectorial growth along the direction of the hemicylindrical micelles can be visualized (Fig. 6C). These "embryonic" structures evolve in size, to produce a mesostructured surfactant film, with a thickness from 40 to 150 nm (Fig. 6D). This implies that continued accretion of CTACl from solution, by the hemicylindrical micelle layer on graphite, leads to the development of a close-packed 5 nm diameter cylindrical micelle inultilayer assembly and is probably best described as a hexagonal lyotropic liquidcrystal film in register with the graphite surface. A surfaceconfined liquid crystal could be the precursor to the oriented hexagonal mesoporous silica films that form on graphite in the presence of TEOS and under acidic conditions. [2341 Soft-imaging AFM techniques of aqueous solutions of CTACl in contact with a freshly cleaved graphite surface provide the first evidence that organized mesostructures grow far beyond the hemicylindrical micellar monolayer and can extend in thickness up to micrometer length scales. This provides new and valuable knowledge for enabling the development of design strategies for controlling the nucleation, growth, orientation, and morphology of mesoporous silica films on graphite. The method should be applicable to a range of substrates.