Monolayer Formation of Submicron-sized Colloidal Particles by Drag Coating Convective Self-assembly

Abstract

Monolayer films composed of ordered particle arrays exhibit unique optical properties, which lead to various potential applications like sensors and antireflective coatings. In this study, we investigated particle deposition processes by using a drag coating technique based on convective self-assembly. Unlike micron-sized particles, 300-nm particles formed submonolayers instead of monolayers. Hence, we modified the technique and demonstrated that reversed dragging, introduction of a film blade, and periodic change in deposition speed dramatically improved the particle deposition process to cover the entire substrate surface uniformly with a monolayer of ordered particle arrays. Furthermore, our modified drag coating process produced monolayers of particles with different sizes of 570, 120, 45, and 27 nm. Thus, our technique is simple and versatile, and is applicable to a wide particle size ranging from microns to tens of nanometers.