Laser-Directed Self-Assembly of Highly Aligned Lamellar and Cylindrical Block Copolymer Nanostructures: Experiment and Simulation

Abstract

Laser photothermal annealing is emerging as a promising strategy for directed self-assembly of block copolymers along with its unique advantages, such as area selectivity, solvent-free ultrafast process, and highly oriented nanopattern formation without substrate prepatterning. We investigate laser-induced highly aligned lamellar and cylindrical self-assembled nanostructure formation by means of simulation as well as experiment. Self-assembled surface-perpendicular lamellar or surface-parallel cylindrical nanodomains in PS-b-PMMA thin films could be aligned by lateral steady scan of focused laser irradiation to attain excellent long-range order over 10 μm length scale. For the systematic understanding of the experimental observation, quasi-static simulation employing successive self-consistent field theory calculation has been developed. Miniaturized simulations of experimental systems could confirm a strong tendency for lamellar domains to grow in the direction of laser scanning. Cylindrical self-assembled domains exhibit similar behaviors provided that the surface prefers one block and the block copolymer film thickness is moderate.