Xingkun Man, David Andelman, Henri Orland
We study block copolymers (BCP) on patterned substrates, where the top
polymer film surface is not constrained but is a free interface that adapts its
shape self-consistently. In particular, we investigate the combined effect of
the free interface undulations with the wetting of the BCP film as induced by
nano-patterned substrates. For a finite volume of BCP material, we find
equilibrium droplets composed of coexisting perpendicular and parallel lamellar
domains. The self-assembly of BCP on topographic patterned substrates was also
investigated and it was found that the free interface induces mixed
morphologies of parallel and perpendicular domains coupled with a non-flat free
interface. In both cases, the free interface relaxes the strong constraints
that would otherwise be imposed by a fixed top boundary (which is commonly used
in simulations), and affects strongly the BCP ordering. Our study has some
interesting consequences for experimental setups of graphoepitaxy and
nanoimprint lithography.
View original:
http://arxiv.org/abs/1109.0833
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