Stanislav Tsoi
US Naval Research Laboratory
Title: Controlling surface van der Waals interactions with monolayer materials
Biography
Biography: Stanislav Tsoi
Abstract
Physical phenomena occurring at the nanoscale often have no analogues in the macroscopic world. In this regard, nanomaterials offer exciting opportunities to create unique physical devices and effects. This presentation focuses on monolayer materials, a class of crystalline 2D solids with a thickness of less than 1 nm, and their unprecedented capacity to modify surface interactions. Forces operating at solid surfaces, such as the van der Waals force and hydrogen bonding, determine outcomes of many common phenomena, from liquid spreading (wetting) to adhesion of particles to bioadhesion. Remarkably, these forces are confined within the nanoscale from the surface: van der Waals within 20 nm and the hydrogen bonding within 1 nm. A simplified picture of such short-range forces effectively attributes them to the surface and a few sub-surface atomic layers of the solid. In this context, the recent advent of the atomically thin monolayer materials offers an unprecendented opportunity to build surface interactions in a bottom-up approach, by sequentially applying different monolayers on top of existing surfaces. Our work focuses on fundamental understanding of how the monolayer materials modify surface van der Waals interactions and this presentation highlights novel physical phenomena, unique to the monolayer materials, such as van der Waal screening.