Temperature-Enhanced Solvent Vapor Annealing of a C-3 Symmetric Hexa-peri-Hexabenzocoronene: Controlling the Self-Assembly from Nano- to Macroscale

Temperature-enhanced solvent vapor annealing (TESVA) is used to self assemble functionalized polycyclic aromatic hydrocarbon molecules into ordered macroscopic layers and crystals on solid surfaces. A novel C-3 symmetric hexa-peri-hexabenzocoronene functionalized with alternating hydrophilic and hydrophobic side chains is used as a model system since its multivalent character can be expected to offer unique self-assembly properties and behavior in different solvents. TESVA promotes the molecule's long-range mobility, as proven by their diffusion on a Si/SiOx surface on a scale of hundreds of micrometers. This leads to self-assembly into large, ordered crystals featuring an edge-on columnar type of arrangement, which differs from the morphologies obtained using conventional solution-processing methods such as spin-coating or drop-casting. The temperature modulation in the TESVA makes it possible to achieve an additional control over the role of hydrodynamic forces in the self-assembly at surfaces, leading to a macroscopic self-healing within the adsorbed film notably improved as compared to conventional solvent vapor annealing. This surface re-organization can be monitored in real time by optical and atomic force microscopy.