The understanding of wetting and capillary effects have a long history, with the most widely known relation being the Young-Dupré equation, relating the wetting angle of a liquid droplet on a flat solid substrate to surface tension/interfacial free energies. Another field with a long history is that of elasticity. When wetting soft materials, the forces exerted by the liquid on the substrate may cause it to deform, thereby coupling elasticity and wetting phenomena. In comparison to the long history of elasticity and wetting, the study of elasto-capillary phenomena is comparatively new, and is becoming of increasing importance for biophysics, micro-fabrication, etc. A material, where the wetting properties, even in the absence of deformation is still debated, is graphene. While understanding the wetting dynamics of 2D-materials is important for applications, these materials can also be ultra-flexible, allowing nanometer-size droplets to induce significant deformations. This makes 2D-materials ideal for studying how elasto-capillary effects carry over to the nano-scale. Although such effects in thin membranes have recently received considerable attention on a macroscopic scale, the cross-over to the nano-scale has not yet been studied. Using large scale molecular dynamics (MD), we have studied wetting and deformation of graphene due to nanometer sized water droplets, focusing on the wetting angle near the vesicle transition. Recent continuum theories for wetting of flexible membranes reproduce our MD results qualitatively well. However, we find that when the curvature at the triple phase contact line is large, macroscopic continuum theories must be adjusted to take into account a variable effective wetting angle.
Videoconferencia vía Zoom con transmisión vía Youtube: bit.ly/YouTube_ICF
Participante: Dr. Andreas Isacsson
Institución: Chalmers University and University of Gothenburg
Fecha y hora: Este evento terminó el Miércoles, 26 de Abril de 2023