| Abstract
| - In this paper, the self-organization of fiber-forming anisotropic molecules is inspected both theoretically andexperimentally. In the first part, a theoretical model which extends the de Gennes theory of thin films toassemblies of strongly anisotropic molecules is reported. The model predicts that solid supported thin filmsmade up of fiber-forming discotic molecules can grow with both tangential and radial arrangement of thefibers, respectively leading to the formation of compact and holed supra-aggregates. These last systems formaccording to the following picture. The tangential growth minimizes the number of unfavorable free ends butintroduces elastic strain especially in the central region of the aggregate. To reduce the elastic strain, somemolecules are displaced from the central region toward the periphery of the growing aggregate, producing alocalized well. In the second part of the paper, we experimentally face the above issue by depositing a stronglyanisotropic disk-shaped molecule (rhodamine 123) onto different solid substrates through a spin coatingprocedure. By employing scanning force microscopy (SFM), the formation of thermodynamically favoredfiberlike supramolecules as well as of compact and holed submicron-sized supra-aggregates has beendemonstrated. The observed phenomena have been found to depend on the interplay of different parameterssuch as molecular concentration, evaporation time, and substrate composition. As main features, both theoryand experiments show that holed supra-aggregates are more stable beyond a critical aggregation size and thatthe formation of holes is favored at high supersaturation. The theory seems valuable in extending previousdewetting models developed for fluid films with isotropic interaction forces.
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