Speaker: Prof. Jacob Sagif - Highly Ordered Silane Monolayer Patterned by Constructive Lithography: A Novel Single-Layer Conducting Material
Self-assembled silane monolayers are remarkably robust one-molecule-thick surface fi lms that may be prepared on a large variety of polar solid substrates by spontaneous molecular self-assembly at the interface with a fl uid phase. The constructive lithography (CL) methodology advanced for their surface chemical functionalization and patterning enables local conversion of the top methyl groups (-CH3) of a highly ordered silane monolayer to carboxylic acid functions (-COOH) while preserving the overall monolayer structure.1-3 AFM with conductive probes may be used to serially inscribe stable patterns of such chemically active surface functions (on the inert monolayer surface) with features varying from hundreds of micrometers to less than 20 nm,1,3 whereas appropriate conductive stamps allow rapid parallel printing of areas extending from micrometers to centimeters.2 Serial and parallel versions of CL may be combined, thus off ering a rather unique chemical tool for the fabrication of continuous monolayer patterns with nano-to-macroscale interconnected carboxylic acid surface features of variable shapes and lateral dimensions.3 A brief overview of this nondestructive surface patterning methodology will be followed by a description of its recent application to the fabrication of artifi cial ionic circuits capable of confi ning the traffi c of selected ions and related electrochemical processes to atomically thin ion-conducting channels with predefi ned two-dimensional layouts, shapes, and lateral dimensions spanning nanometer-to-centimeter length scales.4 Monolayer patterns produced in this manner exhibit some rather unique properties as generic solid ion-conducting entities, i.e. a solid-state material that can accommodate and transport diff erent selected ions and mixtures thereof in the absence of any added electrolyte. Unlike graphene and other single-layer electronic conductors, a conductive monolayer surface of the present type represents an inherently patternable and reusable single-layer functional material, generated by the patterning process itself.4 These features are particularly attractive for device fabrication.
