Wafer-scale, full-coverage, acoustic self-limiting assembly of particles on flexible substrates

Self-limiting assembly of particles represents the state-of-the-art controllability in nanomanufacturing processes where the assembly stops at a designated stage1,2, providing a desirable platform for applications requiring delicate thickness control3-5. Most successes in self-limiting assembly are limited to self-assembled monolayers (SAM) of small molecules on inorganic, chemically homogeneous rigid substrates (e.g., Au and SiO2) through surface-interaction mechanisms6,7. Similar mechanisms, however, cannot achieve uniform assembly of particles on flexible polymer substrates8,9. The complex configurations and conformations of polymer chains create a surface with non-uniform distributions of chemical groups and phases. In addition, most assembly mechanisms require good solvent wettability, where many desirable but hard-to-wet particles and polymer substrates are excluded. Here, we demonstrate an acoustic self-limiting assembly of particles (ASAP) method to achieve wafer-scale, full-coverage, close-packed monolayers of hydrophobic particles on hydrophobic polymer substrates in aqueous solutions. We envision many applications in functional coatings and showcase its feasibility in structural coloration.