Modulating Wettability of Layered Materials by Controlling Ligand Polar Headgroup Dynamics

Integrating functionalized 2D materials into multilayer device architectures increasingly requires understanding the behavior of noncovalently adsorbed ligands during solution processing. Here, we demonstrate that the headgroup dynamics of polymerized monolayers of functional alkanes can be controlled to modify surface wetting and environmental interactions. We find that headgroup dynamics are sensitive to the position of the polymerizable diyne group; thus, the polymerization process, typically used to stabilize the noncovalent monolayer, can also be used to selectively destabilize chain-chain interactions near the headgroups, making the headgroups more solvent-accessible and increasing surface hydrophilicity. Conversely, interactions with divalent ions can be used to tether headgroups in-plane, decreasing surface hydrophilicity. Together, these results suggest a strategy for the rational design of 2D chemical interfaces in which the polymerization step reconfigures the monolayer to promote the desired environmental interactions.