Self‐assembled nanostructures of diblock copolymer films under homopolymer topcoats

Abstract

AbstractTo mitigate the interface energies of block copolymers with high interaction parameters, a topcoat strategy has been experimentally proposed to produce perpendicular oriented domains on a length scale of sub‐10 nm. However, the origin of perpendicular oriented domains and the effect of topcoats on the self‐assembled nanostructures remain to be uncovered. Herein, we use the dynamic self‐consistent field theory to explore the self‐assembly behaviors of symmetric block copolymer films under homopolymer topcoats. It is clearly demonstrated that the introduction of homopolymer topcoats enables a wide formation range of perpendicular oriented lamellae, originating from the fluctuating diblock copolymer/homopolymer interfaces in the process of in‐plane microphase separation of block copolymer films. Our simulation results also demonstrate that the formation range of perpendicular oriented lamellae can be tuned by changing the wetting properties of homopolymer topcoats and the thickness of block copolymer films, but is weakly dependent upon the chain length of homopolymers. Our theoretical findings have wide implications for understanding the formation of perpendicular oriented domains of block copolymer films, which are important for the rational design of self‐assembled nanostructures with new horizons for block copolymer lithography. © 2020 Society of Chemical Industry