Morphology of Symmetric Diblock Copolymers Confined Between Two Stripe‐Patterned Surfaces – Tilted Lamellae and More

Abstract

Summary: We report the first Monte Carlo simulations on the thin‐film morphology of symmetric diblock copolymers confined between either symmetrically or antisymmetrically stripe‐patterned surfaces. Under suitable surface configurations (where the lamellae can comply with the surface patterns and can have a period close to the bulk lamellar period L0), tilted lamellae are observed for film thicknesses D ≥ 2L0; the checkerboard morphology is obtained for smaller film thicknesses. The A‐B interfaces in the tilted lamellae are basically perpendicular to the surfaces in their immediate vicinity, and exhibit undulations away from them. In some cases, the severe frustration imposed by the two patterned surfaces leads to irregular or unexpected morphologies, which represent locally stable states. The efficient sampling of our expanded grand‐canonical Monte Carlo technique enables us to observe more than one locally stable morphologies and the flipping between them during a single simulation run.Tilted lamellae between symmetrically patterned surfaces (perpendicular to z) with a surface pattern period of 1.5L0 and a film thickness of 2.67L0. L0 is the bulk lamellar period and the black curves mark the A‐B interfaces.imageTilted lamellae between symmetrically patterned surfaces (perpendicular to z) with a surface pattern period of 1.5L0 and a film thickness of 2.67L0. L0 is the bulk lamellar period and the black curves mark the A‐B interfaces.

Directed Self-Assembly of Block Copolymers on Sparsely Nanopatterned Substrates

“…The tilted lamella structure found in this study is consistent with that in Wang’s Monte Carlo simulation . Although the top and bottom surfaces in Wang’s Monte Carlo simulation were both fully nanopatterned, which is different from the condition investigated in this work, the tilted lamella structures in both cases are found to be undulated and exist in the relatively thicker films ( D /2 L p ≥ 2).…”

Elucidating the Formation of Block Copolymer Nanostructures on Patterned Surfaces: A Self-Consistent Field Theory Study

“…Upon close inspection, we note that the two network structures are different. In Figure a, the morphology is close to the checkerboard morphology, except that the different regions are connected by bridges . It should be noted that the pattern width is smaller than the natural spacing of the block copolymer.…”

Self-Assembly of Diblock Copolymer on Substrates Modified by Random Copolymer Brushes

“…This competition results in the formation of perpendicularly aligned phases for certain ranges of thickness even for preferential substrates. Similar behavior was also shown using Monte Carlo simulations. , Subsequent work has extended the above developments by focusing on the cases of asymmetric diblock copolymers, multiblock copolymers, − the impact of patterned hard surfaces − and the effects of surface roughness. , More recent studies of diblock copolymer thin films bounded by homogeneous surfaces has elucidated the plethora of mixed morphologies that may occur as a function of the complex system parameter space…”