A Facile Approach to Directed Assembly of Patterns of Nanoparticles Using Interference Lithography and Spin Coating

Abstract

We present a facile approach to the directed assembly of silica nanoparticles (≲ 100-nm diameter) into periodic arrays on flat surfaces using interference lithography and spin coating. Periodic photoresist patterns, used as templates for the spin-coating process, were prepared using interference lithography. Silica nanoparticle dispersions were spin coated on these patterned surfaces, and the resist was removed, leaving periodic nanoparticle patterns on flat surfaces. Parallel arrays and continuous cross networks of particles were fabricated successfully with periods between hundreds of nanometers and several microns over areas of several square centimeters. The morphology (period, layer width and thickness, etc.) of the particle patterns can be controlled by varying the process conditions.

Toward Greener Nanosynthesis

“…[321][322][323][324][325][326][327][328][329] Proper substrate selection affords an additional opportunity to control the morphology of the assembled array, as the final structure typically mimics that of the substrate; that is, planar substrates may support twodimensional arrays, whereas substrates having a relatively linear structure are best suited to one-dimensional structures. Advanced surface treatments including lithographic patterning [330][331][332][333][334] and patterning/stamping techniques [335][336][337][338][339][340] can be used to generate patterned arrays with specifically constrained dimensions, thus improving the versatility of planar substrates, although some techniques (electron and ion beam lithography) lack the efficient, parallel processing methods offered by simple self-assembly on molecular scaffolds. The application of efficient particle assembly methods will remain an area of focus in the pursuit of nanoproducts produced primarily by green chemistry-inspired routes.…”

Emergent singular solutions of nonlocal density-magnetization equations in one dimension

“…(17). Since the weights a 1 , a 2 , |b 1 |, and |b 2 | are constant, two variables suffice to describe the interaction: the relative separation x = x 1 − x 2 of the clumpons, and the cosine of the angle between the clumpon magnetizations, cos ϕ = b 1 · b 2 /|b 1 ||b 2 |.…”

“…Indeed in this framework, it is possible to prescribe the dynamics of the particle-like structures after collapse. Thus, the model provides a description of directed self-assembly in nanophysics [16,17], in which the detailed physics is less important than the effective medium properties of the dynamics.…”

Formation of clumps and patches in self-aggregation of finite-size particles

“…This assumption is used for two main reasons. First, it suits the physics of the motivating problem, namely, mutual attraction of nano-particles [10]. Second, restricting to purely attractive interactions allows one to separate all equations of the type (6,7) into two different classes.…”