3D bicontinuous diamond-like morphologies in thin films of soluted block copolymers

Abstract

As shown theoretically earlier via both weak segregation and self-consistent field theories, ordering of confined molten di- and tri-block copolymer morphologies in the presence of a proper 1D patterned substrate could induce the formation of 3D bicontinuous (in particular, diamond-like) morphologies (DLMs). The purpose of the present paper is to study, unlike the previous studies, how the stable DLMs are formed not in a melt but in a solution of symmetric diblock copolymers with a nonselective solvent that wets the thin film on the patterned substrate. It is shown, via a straightforward self-consistent field calculation of the total solution free energy for various competing phases, that the DLM could be formed in the solutions (with the solvent volume fraction of 0.5), which provides much faster thermodynamic equilibration of the solution as compared to the melt. The last circumstance can ease the production of stable DLMs in thin films of copolymers. The phase diagram describing the stable phases on the plane “the pattern period—the film thickness” is built.