Hierarchical Microphase Behaviors of Chiral Block Copolymers under Kinetic and Thermodynamic Control

Abstract

Chiral superstructures in confined spaces are subtly affected by the complex interplay among various noncovalent interactions, details of which are still inadequately understood. Herein, we report the three-dimensional confined assembly of the chiral block co-polymers of polystyrene-block-poly(d-lactide) and its enantiomer in emulsion droplets and demonstrate unprecedented successive microphase transformations from single helices to double helices with inverted helicity, and then to twisted cylinders in the constructed colloidal particles. The above hierarchical structural transformations of chiral microphases are kinetically dependent and can further transform into thermodynamically stable achiral cylinders with saddle-shaped topology upon solvent annealing. The formation and subsequent structural transformations as well as the final degeneration of chiral architectures provide guidance to understand the chiral evolution at different length scales within spherical confined space and to fabricate biomimetic systems.