Block copolymer assemblies under 3D confinement: from spherical boundary to continuous network template

Depending on the interplay between polymer chain stretching and interfacial energy of the intermaterial dividing surface (IMDS), different self-assembled block copolymer nanostructures can be achieved. Directed self assembly in 2D employing confinement via walls, posts and various surface treatments can improve long range order and induce new microdomain patterns. By applying templates with spatially varying 3D geometric boundary conditions, block copolymers have the possibility to form a host of new morphologies and complex, hierarchical block polymer/template 3D ordered composites. The self-assembly behaviors of a bulk phase lamella-forming polystyrene-b-polydimethylsiloxane diblock copolymer within different 3D confinement boundary conditions are presented. The 3D confinement varies from that of within a simple sphere to occupation of the connected void space of a complex 3D network template. By taking advantage of Slice-and-View scanning electron microscope tomography, large volume 3D information of the polymer/template assembles can be produced at high resolution. The domain morphology, IMDS curvature, polymer chain stretching, and morphological defects are discussed.