Wafer-Scale Full-Coverage 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 stage, providing a desirable platform for applications requiring delicate thickness control such as optics, electronics, and catalytic systems. Most successes in self-limiting assembly are limited to self-assembled monolayers (SAMs) of small molecules on inorganic, chemically homogeneous rigid substrates (e.g., Au and SiO2) through surface-interaction mechanisms. Similar mechanisms, however, cannot achieve a uniform assembly of particles on flexible polymer substrates. The complex configurations and conformations of polymer chains create a surface with nonuniform 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 a collision-based self-limiting assembly (CSA) to achieve wafer-scale, full-coverage, close-packed monolayers of hydrophobic particles on hydrophobic polymer substrates in aqueous solutions. The kinetic assembly and self-limiting processes are facilitated and controlled by the combined acoustic and shear fields. We envision many applications in functional coatings and showcase their feasibility in structural coloration. Importantly, such functional coatings can be repaired using CSA, and both particles and polymer substrate can be recycled.

Automated summary

Self-limiting assembly is an advanced technology in nanomanufacturing processes, which allows assembly to stop at a designated stage for applications requiring precise thickness control. The majority of successful self-limiting assembly cases have been achieved on rigid substrates through surface-interaction mechanisms. However, achieving uniform particle assembly on flexible polymer substrates is challenging due to the complex configurations and conformations of polymer chains. In this study, collision-based self-limiting assembly (CSA) is demonstrated to achieve wafer-scale, full-coverage, close-packed monolayers of hydrophobic particles on hydrophobic polymer substrates in aqueous solutions. The kinetic assembly and self-limiting processes are facilitated and controlled by combined acoustic and shear fields.