A Nanoengineering Approach to Regulate the Lateral Heterogeneity of Binary Self-Assembled Monolayers

Keywords:
AFM, nanofabrication, nanografting, self-assembled monolayers, SAMs, lateral heterogeneity

Abstract:
A new method to regulate the lateral heterogeneity, i.e. both domain size and domain separation, of binary self-assembled monolayers (SAMs) with nanometer scale precision is demonstrated. It involves the utilization of a scanning probe lithography method known as nanografting in conjunction with knowledge of self-assembly chemistry. Unlike other reported ways to control the SAMs products, which focus on either varying the reaction conditions such as the reaction temperature, the total concentration of mixed thiol solution, the molar ratio of the two component thiol species or modifying the reactants by choosing different chain lengths and/or terminal functionalities, our approach targets at the reaction pathway. The reaction mechanism of alkanethiols self-assembly on a gold surface in nanografting differs significantly from that in mix-and-grow methods. Knowledge of the reaction pathways enables development of methods for shifting the interplay between the kinetics and thermodynamics in SAM formation, and thus the heterogeneity of mixed SAMs. By varying fabrication parameters such as shaving speed, and reaction conditions such as concentration and ratio of the components, the lateral heterogeneity can be adjusted ranging from near molecular mixing to phase-segregated domains of several to tens of nanometers.

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Nanotech 2007 Conference Program Abstract