Patterning two-dimensional (2D) surfaces with self-assembled arrays of functional molecules has been pursued for its potential to manipulate the remarkable materials properties of substrates like graphene, MX2, and other novel 2D surfaces. Demonstrations of controlled self-assembly processes by tuning either intrinsic variables (molecular design and symmetry) or extrinsic properties (temperature, concentration, solvent, capillary flow, and substrate) are well documented. Here, we investigate the impact of chemisorbed species on the self-assembly of different molecules on the graphite surface. We demonstrate how chemisorbed molecules on graphite surface can impede molecular self-assembly at the liquid-HOPG interface. Chemisorption is facilitated through aryl radical attack of the graphite surface after electrochemical activation of diazonium species. The resultant sp3 hybridized sites act not as nucleation points but as barriers to obstruct the self-assembly processes. Self-assembly obstructions include the creation of domain boundaries, stacking faults, and poor/no assembly in laterally confined areas (~8 × 8 nm2). Annealing treatments demonstrate the ability of the self-assembly to minimize the perturbations created by the defects. Selective removal of the covalent defects via in situ nanolithography provides a handle to control Oswald ripening. This work represents a generalized platform for fundamental perturbations studies on nucleation, growth, and ripening processes within 2D physisorbed self-assemblies.

Chemisorption impacts on physisorption: Perturbations of 2D self-assemblies at the liquid-solid interface

253rd National Meeting (2017)

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