Graphoepitaxy of hard spheres into square lattices

Abstract The 2D directed self-assembly of micron-sized hard spherical particles within square confinements is studied theoretically and experimentally. Grand Canonical Monte Carlo simulations are used to predict the equilibrium packing structures of particles in square wells of specific dimensions. Spin coating and mechanical rubbing processes are used for the directed self-assembly of a monolayer of particles. The precision of the graphoepitaxy decreases as template size increases. Both simulations and experiments show that graphoepitaxy of square lattices vanishes with square templates of side length greater than five times the particle diameter. Missing particles and polydispersity of particles are two main causes disrupting the square packing structure in cells of three to five particle diameter side length.