Understanding Dewetting Transitions On Nanotextured Surfaces: Implications For Designing Surfaces With Improved Wettability

Despite the early promise of superhydrophobic surfaces, their widespread technological adoption has been dawdled by the ease with which water can penetrate the surface texture, resulting in a breakdown of superhydrophobicity. Furthermore, this breakdown is believed to be irreversible, because large adhesion barriers impede the dewetting of the surface texture and the concomitant recovery of superhydrophobicity. Using molecular dynamics simulations in conjunction with advanced sampling techniques, in this thesis, we challenge this conventional argument. We show that while large barriers do typically impede the recovery of superhydrophobicity, it can nevertheless be recovered spontaneously on nanotextured surfaces, wherein collective water density fluctuations lead to non-classical dewetting path- ways and reduced dewetting barriers. An understanding of the complex dewetting pathways further enables us to uncover principles for the design of novel surface textures on which dewetting barriers vanish and superhydrophobicity can be spontaneously recovered. Our results thus promise to pave the way for robust superhydrophobic surfaces with widespread applicability under the most challenging conditions from applications involving sustained underwater operation to enabling drop-wise condensation in heat exchangers. Along with recent advances in the synthesis of surfaces with nanoscale texture, work in this thesis promises to revitalize the field of superhydrophobicity and its class of problems, from its prevalent trial-and-error approach to the rational design of surface textures.