| AVS 58th Annual International Symposium and Exhibition | |
| Applied Surface Science Division | Wednesday Sessions |
| Session AS+BI+NS-WeM |
| Session: | Advances in Scanning Probe Microscopy |
| Presenter: | Vladimir Korolkov, The University of Nottingham, UK |
| Authors: | V.V. Korolkov, The University of Nottingham, UK S. Allen, The University of Nottingham, UK C.J. Roberts, The University of Nottingham, UK S.J.B. Tendler, The University of Nottingham, UK |
| Correspondent: | Click to Email |
Chemical decoration of surfaces with various molecules and supramolecular structures has been a major strategy for introducing new properties to both organic and inorganic materials. Amongst these properties are wettability, biocompatibility, sensing properties, catalytic activity, optical properties and adhesion. Most of methods for surface modification include molecules binding to the surface via stable chemical bond. Recently methods have been developed to modify atomically flat surfaces with periodical porous molecular structures, termed 2D-supramolecular networks. The networks are commonly composed of two types of molecules serving different functions e.g. joints and ribbons. Such 2D-structures bring forward a unique surface property - a spatially controlled adsorption with almost single molecule precision.
Most networks reported in the literature have been studied using UHV STM on metal substrates and, to a lesser extent, on HOPG and non-conductive substrates. Here we present a study, utilizing both ambient STM and AFM, of 3,4,9,10-perylenetetracarboxylic diimide (PTCDI) - melamine networks deposited on Au(111), HOPG and MoS2 substrates. AFM imaging was performed using PeakForce Tapping AFM (Bruker Inc.) and Torsion Resonance (TR)-AFM. Both STM and AFM were able to resolve a clear periodical network structure for all substrates after exposure to a solution of PTCDI and melamine molecules in dimethylformamide at 373K. AFM images show that the network forms a monolayer on both HOPG and molybdenite substrates, and also that most of the HOPG surface is covered with network structure, with some minor defects. In contrast the Au(111) surface was mostly covered with network multilayers as suggested both by TR-AFM and STM. AFM also revealed that the network structure on HOPG and molybdenite remains intact for several hours in the ambient and can be stored in N2-ambient for up to ~24h.