Phase Behavior of Block Copolymers under Conical Confinement

Abstract

Constraints imposed by nanometer scaled confinement lead to the changes in bulk equilibrium behavior of block copolymers (BCPs). Especially, cylindrical pores with diameter corresponding to the equivalent length of several copolymer chains have been employed to investigate the influence of two-dimensional (2D) confinement on the behavior of BCPS. In this study, poly (styrene-b-butadiene) block copolymers was confined within conical pores and their morphologies are investigated using electron microscopy. Anodized aluminum oxide (AAO) templates with conical pores fabricated using multi-step anodization were used as confining matrix. On the basis of detailed observation, we demonstrated the effect of pore size, shape and surface energy on the phase behavior of block copolymers under conical confinement.