  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.
