Alignment and Structural Evolution of Cylinder-Forming Diblock Copolymer Thin Films in Patterned Tapered-Width Nanochannels

Abstract

Control over the orientation of cylindrical block copolymer microdomains and the position of dislocations using tapered nanochannels is herein demonstrated. Dislocations are introduced periodically as the channels become progressively wider. Our high-temperature atomic force microscopy (AFM) enables us to probe real-time and real-space dislocation movement directly. Upon annealing, dislocations are observed to move to their equilibrium positions, where the average free energy of the polymer chains reaches a minimum. Smaller confinement widths impose a powerful guiding field for templating domain alignment, as the deviations of the dislocations at the narrower end of the channel from their equilibrium positions are minimal. Finally, the fluctuations of dislocations across the wedge are studied under different temperatures, and the perpendicular diffusion coefficients and activation energy are determined. These experiments demonstrate the ability to control the placement of periodically located dislocations...