Self-Assembled Morphologies of Poly(styrene-b-1,4-butadiene) Confined within Cone-Shaped Templates

Block copolymers (BCPs) self-assembled under nanoscale confinement have distinctive nanostructures, which do not appear in bulk state. Especially, depending on different dimensionality of confinement spaces, shape and morphology of block copolymers and their optical properties are affected. In this study, we report phase-separated morphologies of polystyrene-block-1,4-polybutadiene (PS-b-PB) confined in conical templates with various size, shape and surface properties. Based on experimental observation using transmissional electron microscopy (TEM) and theoretical calculation of simulated annealing method, we found that phase separation of PS-b-PB in the conical confinement system are competitively affected by three thermodynamic factors; (1), (2) the interfacial energy between two different block and surrounding environment (air and substrates) and (3) the entropic penalty associated with large curvature at the vertices of conical pores. In addition, 3D imaging of TEM tomography were also performed in an attempt to identify internal nanostructures of BCP thoroughly.