Superhydrophobic and Water-Repellent Coatings with Dual-scale Roughness based on MXene/Polymer Nanocomposites

Two-dimensional layered MXenes are utilized as functional additives for the development of superhydrophobic and water-repellent coatings prepared using waterborne nanocomposite formulations. The necessary hydrophobicity is introduced utilizing a low surface energy water-soluble fluoroalkyl silanol, whereas the nanoadditives are introduced to create the necessary surface roughness. While traditional methods typically employ spherical nanoparticles to achieve nanoscale surface structuring, the flake-like structure of Ti₃C₂Tₓ MXenes introduces roughness that extends into the micron-scale. Different smooth substrates were coated and the surface properties were investigated as a function of the additive content. Moreover, ternary nanocomposite coatings were developed with MXenes and alumina nanoparticles. This combination results in hierarchical surface structures (with micrometer- and nanometer-scale roughness), achieving excellent water repellence with significantly lower additive concentration than the one needed when single nanoadditives were used. This study highlights the potential of MXenes as an innovative additive for next-generation water-repellent coatings.