Wetting of a dynamically patterned surface is a time-dependent matter

Wetting of a dynamically patterned surface is a time-dependent matter In nature and many technological applications, aqueous solutions are in contact with patterned surfaces, which are dynamic over timescales spanning from ps to μs. In biology, exposed polar and apolar residues of biomolecules form a pattern, which fluctu- ates in time due to sidechain and conformational motions. At metal/ and oxide/water interfaces the pattern is formed by surface topmost atoms, and fluctuations are due to, e.g., local surface polarization and rearrangements in the adsorbed water layer. All these dynamics have the potential to influence key processes such as wetting, energy relaxation, and biological function. Yet, their impact on the water H-bond network remains elusive. Here, we leverage on molecular dynamics to address this fundamental question at a Self-Assambled Monolayer (SAM)/water interface, where ns dynamics is induced by frustrating SAM-water interactions via methylation of the terminal -OH groups. We find that surface dynamics couples to the water H-bond network, inducing a response on the same ns timescale. This leads to time fluctuations of local wetting, oscillating from hydrophobic to hydrophilic environments. Our results suggest that more than average properties, it is the local—both in time and space—solvation that determines the chemical-physical properties of dynamically patterned surfaces in water.